[sf4] Couple of questions coming from GG XRD

I got USF4 a few months ago and never really gave it a chance. After finding out today that a few friends play I'm going to now that I have someone local to play against. However, I typically play more anime fighters Blazblue and recently Guilty Gear. So, for my questions....

1. What are the major mechanic differences other than feeling slowing, lack of burst, and lack of Roman cancels?

2. Any character suggestions? My main in BBCP/Ex was Nu-13 with secondary being Litchi, main in GG Xrd is Millia with secondary being Ky.