1. Head to the character subforums in the Blazblue section. There are combos, general strategies and usage, videos, and tons of helpful stuff.
2. The input is right>down>down+right or 623(Look at the numpad on your keyboard, each number is a direction, 5 being neutral)
4. The way I tackled the game is by playing Ragna for basics, then jumping around with Taokaka, Hazama, Hakumen, Tager, and Tsubaki, until finally landing on Lambda and being happy there. Just play around with characters until you find one you like. Past that, just play with that for a bit, get more of a feel for it, what all your different moves are, get a feel for your spacing, from there get into combos and more advanced techniques.
Though in the end I'm still pretty scrubby, but I hope this helps you out. The game is fun as heck and it always feels good to improve.
