There really is not set pattern for where to ward every game. In lane, I usually maintain a ward in the bot lane tribrush and one outside the dragon pit if I can do it safely, but those are really the only fixed points I always try to ward. I usually do not use stealth wards at the jungle camps unless I have reason to expect enemy movement in that area, or if I am pushing or defending an objective in that territory and did not have a pink ward handy. There isn't really a good rule about how often you should ward, but keeping four wards up at all times is a good rule to follow when you just need to get in the habit of warding more reliably. Your goal is to ward enough to feel safe while near the objective you are currently focusing on pushing or defending. If it is well warded, it's fine to keep those sightstone charges until the old wards expire or you push into new territory. The judgement comes with practice, and that's not something I can easily teach you in this post. Watching professional play may not be ideal for low-level players, but I think watching a couple matches really helps give an idea about effective warding. (The first games I watched were the world championship finals this past year, and I learned a lot.) Sorry if I can't be less ambiguous than that.
It was a big revelation to me when I learned that my favorite build and build path was not appropriate for every situation! That judgement should come with more experience and knowledge of other champions and match-ups. Crucible is a solid support item and is often prioritized at high levels of play, but it tends not to be terribly useful at low levels. I actually need to practice using it, myself. I always finish my Ruby Sightstone in the late game if I don't have anything else to spend gold on, sometimes a little earlier if I think the health and extra ward charge will actually be significant. There really is no reason to sit on an unfinished item and a gold surplus unless you are playing an intentionally low-health build.
There isn't a lot you can do about flaming teammates except continue to be encouraging and sportsmanlike. Sometimes you can tactfully point out that they are behaving inappropriately or remind them that they won't play any better if they spend their time typing, but don't count on that working all of the time. The best thing you can do is just set a good example by complimenting good plays by successful and unsuccessful allies (and opponents) alike and encouraging people who are having a hard time.
Supports definitely can make game-changing plays, but they usually still rely on allied damage dealers to take advantage of their set-ups. Multi-target crowd control, well-timed disruptions and Mikael's actives, and even solid peeling can change a game in your favor. With Sona, Bard, and Janna, this will usually take the form of significant engages and counter-engages (I admit that I have never played Janna outside of ARAM and have never played Bard, so I don't know them terribly well). At low levels, shot-calling can also make a big difference. As a support, you probably have a better awareness of the map than most others on your team, and most people will follow you if you encourage them to push a vulnerable objective, especially if it already or easily warded out. Take advantage of this and get obsessively (not really) focused on objectives.
If the game ends after twenty minutes, I will usually have placed roughly one ward per minute in total, with some variation, typically in the 30-45 ward range. You may not need to ward as much on your own if your allies are doing a solid job, but you'll probably be carrying the warding burden mostly on your own until you climb a fair ways up the ladder (I think, I'm still playing with golds at the best, so I don't know if warding actually gets better).
OK 
I'm sorry if that mostly sounds like a repeat of my first post; I'm not terribly good at describing these topics without pictures or discussing specific cases. Happy farming!