Hey no problem, it's always great to see someone willing to learn!
Your overall plan is pretty solid, and if you're not chasing kills then you're definitely doing it right. For CS, I'd recommend trying to get 8-10 CS/minute if you're able to. Viktor is super potent in pushing out waves once he's gotten his first upgrade.
Winning the lane is super important, you're absolutely right. The hardest part is being able to transition your lead into objectives and affect other lanes. If you're consistently winning your lane, that's great and keep up the good work! If you feel the extra AP helps you then by all means keep doing it!
Vladimir definitely is a 1v5 heavy champion, and can easily out-sustain nearly all champions you'll run into as well, you're 100% correct. The issue, like you said, is being able to scale in time. Vladimir definitely loves him some CDR, and does very well with Spirit Visage. He's in a similar boat to Gangplank, where when picking him you almost have to have the team on-board with "Just give me time!" The main difference is his laning presence, as he tends to do very well in the current meta being mana-less and able to survive for essentially ever in lane to maximize his back times.
You're doing great with your overall plan for going into lane though. Try to mainly focus on CS as well as denying/harassing the enemy when they attempt to go for theirs. Often times it's more beneficial to poke the enemy laner out and deny them precious XP/Gold that they would normally be able to get. Champions still earn XP while dead from nearby sources, however if they're at their fountain they are far out of reach of anything aside from map-wide XP.
Late game picks are always an issue when the death timers start getting out of hand. If your teammates are the ones getting picked, there's not much you can do about it aside from being near them and asking your team to group to avoid it. Try to keep warding up (you're consistently putting more wards than your teammates, good job with this!) to help them out, as many people neglect to use their free trinket wards.
You're correct as well with glass cannon style mages, they are in a similar boat to assassins: When ahead, you stay ahead and can delete most anyone on the map, however when behind you are much less useful. If you're snowballing and winning your lane, then try and look for those juicy picks yourself. It's a mind game to a degree, if you see a massive wave of yours pushing top into the enemy tower and the enemy ADC is nowhere to be seen while his team is in a siege elsewhere, he's likely going to be greedy and try to pick up that XP/Gold solo. This is the perfect time to greet him where he is not expecting you and likely unwarded. Sitting in a bush for 15-30 seconds can sometimes be game changing, as with Viktor/Vladimir you have more than enough raw damage to delete them before they can even react.
Both Viktor and Vladimir make fine solo-queue champions as they are relatively safe to push out waves and can roam efficiently. Try to come from behind enemies where they are least expecting you, if bot lane is sitting under tower at 30% HP and don't run to their T2 towers when you roam down from the river, go through the enemy's jungle and sit in the bush. At this point, they're a free kill for you, as the tower dive with your damage is almost guaranteed to kill them. If they start running to T2 tower then, great! They have essentially panicked and have screwed themselves over from any protection a tower would provide. It also lets you know that they have a ward in that bush. Control Wards will definitely be your friend when looking for picks, as you can drop one and literally AFK on top of it if you suspect an enemy may path near you soon. The Sweeper upgrade also greatly assists with this. If you spot out a ward, chances are about 50/50 that the enemy will react to it. If you notice they start pathing towards you, run for the hills as you will likely be collapsed upon. If they don't react, kill the ward and judge their reactions. If they begin hiding in the Fog of War, they've likely spotted you out and are playing safe thinking you are there. Even if you leave at this point, your job is done and you have created more threat across the map. If they stay and play aggressive, they likely haven't even noticed you and are tunnel-visioned into the game at that point. Now you can freely kill them.
You'll find a LOT of players tend to want to push their advantage hard and carry 1v9 - this is very common for champions like Yasuo and Riven as well. I've had a game where I played Skarner Jungle and went to gank a Yasuo top. I forget who my laner was, however I simply walked up to Yasuo, E -> Stunned him, and got him to blow his Flash. I walked away into the bush, and no more than 3 seconds after disappearing into the Fog of War, Yasuo was back at it again dashing through waves like his life depended on it. Now he has no Flash and was a free kill, so we took it - it wasn't even satisfying just walking up and killing him so freely. The enemy Yasuo then proceeded to flame me for camping him, as well as his jungler for not babysitting his lane for him. The game was over rather quickly after that. Try to look for free kills in that regard. With Viktor you bring a massive zone with your W, and if enemies don't have a Flash you can almost guarantee a kill inside of it.
You can use F2-F5 (F1 is yourself) to take a look at your teammates. Try to see who will benefit you the most from helping them. If your ally Riven is spam "?" Pinging everyone and is 0/5/0 with 30 CS at 10 minutes, she likely won't be any help to you or your team. If your ally Ashe is 0/2/3 with 80 CS at 10 minutes, she will likely be more help. Your jungler will be a large factor in your team's well-being, however as mid lane you can affect the enemy jungler more so than other lanes. Try to help them out and roam with yours - both for easy kills if you spot someone out, as well as protection, as most junglers will be fairly tanky or an assassin (depending on what the team needs) and will generally throw their life on the line to get their laners an advantage.
Your biggest advantage in this game in knowledge. By guaranteeing that you are a superior player by being able to place efficient and effective wards, know when the enemy is at a disadvantage (i.e. Blitzcrank's hook is a 20-16 second cooldown from Ranks 1-5 without CDR, if he throws it out he has a large dead-zone where little to no threat is posed), and know when you have certain powerspikes is 1 more than the enemy is guaranteed to have. The smallest of numbers can make the largest of differences. Camille before Trinity Force or Sheen? Probably going to tickle you. Camille late-game? Probably going to take half your health with a Q in true damage.
Check out some of the high-elo junglers for macro-plays. While micro-plays (mechanics) are incredibly important, being able to out-macro the enemy team will gain a more significant advantage in this game. Junglers like taking candy from babies and preying upon the weak. We tend to starve out the enemy team more so than make ourselves stronger. By starving them out, you make them weaker and force them to hit powerspikes far later in the game - if it even gets to that. This is why a lot of high ELO players go the whole "open mid" route and call "GG" after Rengar (or other snowbally champions) has 3 kills at 5 minutes, as the game is incredibly difficult if the enemy team plays perfectly at that point. Rengar will now dominate your allied jungler without assistance, and will freely solo-kill him making himself stronger, while simultaneously farming YOUR jungle as well as his, making your own jungler beyond useless. He will also hit level 6 much faster and transition his power into the lanes, effectively shutting down your team one by one. This forces your team to group sooner, and thus negates any split-pushing, as Rengar will simply assassinate the solo target if they have no assistance.
The same example can be applied to mid lane. If Lee Sin comes and help you grab a free kill on Viktor and you are able to pick up say, a Lich Bane on your first back while the enemy laner has a double Doran's Ring setup, you'll absolutely crush your laner and force them to play safe. If they don't, kill them or push out the wave, and look to rotate with your jungler (or solo if they are busy). Transition your power into other lanes quickly and efficiently by forcing the enemy laner to choose whether they want to protect their tower and maintain Gold/XP through CS, or if they want to match your roam and possibly end up farther behind. Usually they will avoid the latter, as it will make them even more useless. This is why Aurelion Sol and Taliyah have been such contested picks in professional play, as they will quickly push their wave and run to another lane while being able to return to theirs before they miss little (if any) Gold/XP.
Try to protect yourself as well as look for kills that nobody would think of as well. If the enemy jungler is Hecarim, Elise, or any other mana-intensive champion that is guaranteed to start Blue Buff, try to predict their pathing and place wards on the proper side, especially if you are playing aggressive. If there is nobody to kill in enemy lanes and nothing really that will benefit you from roaming, you can still check out the enemy jungle. This works doubly effective if you are ahead, as you can likely solo-kill the jungler. Even just running and checking if their Red is up and placing a deep ward will help to protect your team as well as yourself, and can help you immensely with snatching up free kills. This works especially well if you have an active top laner with Teleport, as they can utilize it to TP behind the enemy with deep wards. If you notice the jungler has <20% HP and is doing Raptors, walk over and kill him with the vision you've gained yourself. This will likely put him on tilt and will certainly put him behind in Gold/XP, while pushing yourself farther ahead. At the very least, you can bully him off of his camp or steal it.
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is an extreme example (now he's nerfed but remember when he was strong) or what Supports are fundamentally about. Just denying good plays from happening. Oh you calculated it so well and went in? Think again, I'll just swallow (except now its shield/heal spam).
late game when you are out ranged and the enemy team is ahead with the picks and the range)... so I have NO IDEA what to do when we are faced with repeated 4 v 5s because our team keeps getting picked off.
can take on multiple enemies at once (or at least he can for now, next patch they are nerfing 
) but we lose so many games BEFORE I get to scale.