For ADCs, if you want someone that's simple to learn and understand, play Cait. Learn to harass and CS at the same time with her and such. If you really like Draven, go and get him! Expand your champ pool as much as you can. But yeah, Cait is one of the easier ADCs to learn to kite and all that ADC stuff. But your playstyle (since you said that you liked Draven may be aggressive and hard-hitting) could suggest that you should try playing the stronger ADCs, like Draven, Lucian and others. It's just about how you prefer to play really. Master Yi is a melee carry btw.
For supports, Shen isn't much of a support really (he can be and it's fun to play but eh). It looks like you're more the tank support player, so try Leona and Braum when you can.
To play support: You're basically the guy that makes or breaks the bot lane imo. You're not JUST the ward bot that support used to be in S3. Of course, buying wards and keeping vision is still important, but supporting goes beyond that. Since ADCs are more focused on farming and trying to get their items for their later game spike, your job as the support is to protect them or make the enemy laners' lives miserable. It honestly depends on the champ you're playing imo.
Alistar, for example, is great at disengaging enemies from his ADC. So when you get into trades with the enemy laners and it's not going your way, you shove their ADC/support away and get your ADC to safety. Alternatively, Alistar can go in and be the all-in-initiator for your ADC. Just run up to them, slam them into the air and shove them back.When I play Lulu, I tend to go hyper aggressive on the enemy laners. When I'm playing Janna, I tend to step back and stick close to my ADC for peel.
As I said before, it really depends on who you play. Also depends on your co-laner. If they don't want to go aggressive, don't just charge in every time and expect them to back you up. Supporting means you have to be really flexible in what you do game-to-game.
When laning ends, always remember to keep wards up and to tell people to ward as well. Get red trinket and de-ward the map. You also need to purchase the proper items. Don't rush the same items that you always buy every game. If their team is mostly AD, consider getting a Frozen heart or randiuns. If there's a lot of AP, get locket of solari, vice versa. But yeah, support is mostly being flexible in order to help win imo.
Just my two cents.