1. Are the side characters going to also gain/lose weight as the story progresses along with having their own plot
Yep!
2. Is the story going to be a bit of weight Role reversal in a sense with the main cast?
Depends what you mean exactly. Hibiki is always the fattest one, but the others do get fat eventually.
3. how many more characters are their going to be in future?
Just Maki, she's already in the Advance (patreon only) version. Yuno's mom will also show up (and is very fat), but only for a few scenes.
