Those are some good points, most of them I can agree with. I'm just curious which casters you find to be useless as compared to which ones are worth playing. I feel like fiddlesticks is one of the better ones, annie as well. I like to play anivia and morgana from time to time, but after the early game I feel like some of their usefulness diminishes.
Wards are good. Put a vison ward in your lane if a stealth character likes to hang out there. Start putting sight wards next to baron when you reach about level 12, putting some by dragon is good too.
One thing that I found about is you can check the profile of top players. Check the top 500 elo list, or even people you played against. This can give you information about what champs they like to use, what items are good on those champs, and what runes and masteries they like to use. If they are good players, their setup is also likely to be good.
Be very cautious when you are alone and enemies are unaccounted for. If you're farming off minions or taking down a tower, the enemy can see you, and they will go after you. This can sometimes be turned into a bait tactic, but usually it will end in your gankrape if you stay out in the open too long.
Don't put yourself needlessly in danger. It's more difficult to asses later, but in the laning phase, if all you can do is stay exp range and not killed, that's good enough. Hopefully you can score some last hits and harass, but if you got stuck in a tough lane, do whatever you have to do to not die.