1. Klazen's tutorial should still work for studio, though you might need to change some object names. I've also bugged Klazen to edit the post now that there's a good studio engine, but oh well.
2.
Yoyo's engine is the main engine for studio, and it's good.
3. Make whatever kinda game you wanna make! Though keep in mind, don't make your huge dream game first. Start out by finishing one or two smaller games, then you can go bigger. Good luck making fangames!