Long-time casual player coming back to ranked, need advice on roles and matchups

Sinister Strife here again, asking for more advice. I just did my ranked placement matches and got into Silver III, which was the same as last season. I'm getting used to the mindsets of other silver players so it's not all bad. As for my background, I've played LoL casually for roughly 3 years now. I've played ranked in Seasons 3 and 4 but never played it much and never got past silver. But I've got a hefty number of games on my belt so assume I have adequate game knowledge, please.

Anyway, I've been an ADC main for as long as I can remember, with a heavy preference on support and mid as secondary roles. So in general, I'm experience with the workings of the mid-to-bottom side of the map. I normally stick to champions that scale well into mid-late game and are good teamfights. For example, my best ADCs are Varus,Sivir, Jinx(All of whom have good teamfight), and Lucian(I guess he'd be more of an all-around ADC), and my best mids are the more support-ish utility mages like Karma,Lux, and Orianna. As for supports I normally play Nami, Sona, Karma, Leona, and sometimes Janna. Again, lots of utility, so I'd say that's my strong point.

My only problems are top lane, jungle, and in some cases mid. I have plenty of experience with both bot lane roles and I'm pretty confident with them. I'm somewhat confident with midlane, but my rather passive/supportive playstyle mid seems to get easily trumped by more aggressive/roamer midlaners. Top lane is somewhat troublesome for me, as most people in lower elos love to play heavy duelist/splitpusher toplaners, as well as taking ignite over teleport for early kills. Pair that with the fact that my playstyle normally revolves around supporting from a distance with either utility or ranged DPS and therefore, I have little to no experience reading other players moves and outplaying them in 1v1s, and you get a player who is VERY easily bullied in toplane. Jungle is even worse, as I'm very hesitant about early roaming and decision making and will often get stuck wondering where on the map to go. Most of my jungle games fail since I fail most ganks and I also get counter-jungled pretty easily, so I've given up on trying to jungle well. I can play 3 roles confidently and can at least carry my weight in 1 other. That's 4 out 5 roles I can play, so it's good enough for me. The only thing I need from you guys, the community, is a bit of advice on how to improve those other roles. Like I said before, I'm pretty confident in both bot lane roles, so I just need some pointers on mid and top lane.

Mid Lane My best mid laners are supportive ones like Orianna, Karma, and Lux. I also used to play a LOT of Viktor and a little bit of Swain in S3 and S4, so I have experience with them too. Generally all of these champions are good in large fights due to their AoE and scale fairly well with items so I mainly focus on farming in the laning phase. My problem is when I either run into lane bullies or heavy roamers. As a midlaner, I've always been told "If you're playing against a heavy roamer and you can't safely follow them to counter-gank when they roam, just ping them as missing, hope your laners will back off, and push mid lane so the enemy misses CS while they're gone." So that's mainly what I do. Unfortunately, half the time even though I ping the enemy midlaner THE SECOND they leave lane, my laners don't back off and end up dying most of the time. This makes me wonder if I should at least try to follow, and risk getting killed, to see if I can save my laners. Also, some assassins give me trouble in lane post-6. One ranked game I played last night as Orianna vs a Fizz, we went mostly even pre-6 in lane, though I did have a bit of a harass advantage over him. After we both hit 6, he doesn't immediately engage, but after a few minutes of farming more waves, he suddenly throws his ult on me and rushes me. Seeing as how he had no lead on me(Neither of us had a kill yet, and we both had barely enough gold to have basic items built. I had a chalice and I think he had a sheen and that was it), I thought I could survive his burst and at least scare him off. I shield myself, pull him in with my ult as he lands on top of me and continue to combo with Q and W. We both throw down ignite on each other, I proceed to kite backwards with AA's as I wait for cooldowns, but eventually I go down while he has about 2 bars of health left. So I guess my point here is not knowing when I can or can't survive an enemy assassin's burst. Again, I'm used to being able to survive burst since I play 3 midlaners that all have self-shields, so this really caught me off guard.

Top Lane Unfortunately for top lane, I don't really have a set champion pool. I used to play a lot of Vladimir and Nasus in season 2(Though this was in normals since I didn't do ranked back then), and Malphite, Wukong, and Renekton in season 3. Every now and then I might have played Jax or Jayce, though I never developed much experience with either in any season. My main problem with top lane is that I'm not used to committed 1v1 fights. I'm used to poking and harassing the enemy and short trades using autos or skillshots, so when it comes to going all-in with a melee vs another melee, I never know what I can or can't win, so my natural instinct tells me to just let the enemy toplane bully me from level 1 and just play passive and farm. This is extremely bad against snowbally bullies like Riven. I think in one of my placements matches I even had to play against a Riven as Vlad and ended up feeding very badly. Like I said before, she took ignite while I had teleport, so all it took was one kill before she started snowballing against me. She would 2v1 me and our jungle Lee so the jungler couldn't help. I couldn't stop her from taking towers either so I had to leave lane, pretty much. Needless to say, it was a very embarrassing game. With top lane, I need some serious advice on how to play against lane bullies like her, and since I'm just naturally not good at 1v1 matchups in general, I need a pool of toplaners that naturally scale well into mid-late game and are good teamfighters. Malphite and Wukong already come to mind since both have heavy CC ultimates. Nasus also comes to mind due to his insane lategame, but I've been told he's not the best at teamfights. If someone could recommend me 1 or 2 good toplaners that fit my criteria so I could round out my champion pool, that would be great.

Before I end off this thread, I have one other general question. I've heard from a lot of people that it's better to just mute every other player in every single one of your matches to avoid the toxicity, since talking and arguing will just distract you from the game. Normally I never say much in game aside from the ocassional "Good job/nice work", or "Thanks", but I do seem to get raged at a lot and when that happens I'm always tempted to at least defend myself against the rager. Not exactly raging back at them, though. I just defend myself against any of their accusations or insults. Would it be better to mute everyone at the start of every game to avoid all unnecessary talk or only mute someone when they're being openly toxic? Because honestly, I can't help but take some of the insults to heart. I know my own flaws and I work on them. For example, sometimes when I ADC I forget that a teamfight is about to happen and I end up farming a lane while my team loses a fight. Yes, I would rather be in the fight, because like I said: teamfights are my kinda thing, but sometimes my tunnel visioning on huge, free waves of gold gets the better of me. And of course, there are always going to be people that think that a few flaws in someone's playstyle means that they're automatically bad. I can't tell you how many times I've been told I deserve to be in bronze just because of a few of my playstyle flaws that I'm working on fixing. Normally I wouldn't listen to them, but after hearing it so many times from so many different people its hard not to think that they might be right. So...should I just mute everyone and leave post-game chat immediately after games end so I can avoid people giving me hell? It gets very demotivating, and I certainly don't need to be demotivated if I'm in the middle of playing ranked.

I'd appreciate all advice. I seem to have to make these kinds of threads every once and while asking for different pointers so I'm open to pretty much anything.