[Zen]

If this is just a rent you shouldnt worry much about technical stuff and just have fun with it.

1. This game isnt about huge combos, some moves do link into one another but you should really start with basics, for example as Ryu the oooold combo goes like jumping fierce(hp), crouching forward (mk), hadoken, just the crouching forward-hadoken part works great as a poke with push back, you can finish it off with any of his special moves (tatsu,shoryu). combos in this game go around linking moves that give you enough of a frame buffer.

2. the ultra should be on the character's move list, im assuming by lesser ultra you mean the ex moves, in this game you get a super that fills up normally as you attack (ryu's being 2 fireball motions and a punch) and the ultra which fills up as you get attacked, you can use it at half full or wait till its complete for a lot more dmg. (ryu's being the same 2 fireball motions and all 3 punches)

3. I dont really play Rufus, so whatever info I could give you on him would be scrubby.

4. Practice makes perfect, specially against a human opponent.