1.)  are all the sprites moving?  it's probably no big deal to keep separate .gsms for each character atm.  it makes it easier later if modifications need to be made.  that's a lot of characters btw.  do they all move?

2.)  doesn't matter, just be consistent, unless i misunderstand the question

3.)see the other thread.

4.)  it depends.  how many sprites actually have left and right?  if it's just 1 like in the first game, then it's not worth it since the routine is probably larger than the extra sprite.  can't recall how much big the routine is, but if it's all 20+ characters (or however many characters 98 is), it's probably a good idea.  especially since it's gs.

do you want me to work on both at the same time?  they kinda have really big similarities.  that being said, I'd kinda rather get LL1 done first.