Not the creator but..
1. Seems non-essential but I think a rolling sound, unless you're an expert sound designer, would distract more than help. I know when I'm rolling and when I'm not.
2. That's because you can't jump/dive while in roll mode often, or when slightly in the air.
4. This is still an issue in an otherwise mostly fast-paced game.
5. I suggested fun hats but we'll see ^^