The lack of punctuation made me a little dizzy, but I'll do my best to answer your questions ;)
1. There will be more side girls and one-shot girls, but no more main girls (there's already over 50 girls in the game... I have no self-control)
2. There will be more events for the side girls, yes, but they're not main girls so don't expect them to have the same level or amount of events
3. I don't know what "the group of the proxies" means, sorry
4. Yandere mode just opens up some Gwen events in Act Two - nothing permanent happens to anyone else, so you're not missing any key story beats if you turn it off
Hope that answered most of your questions :) If you have more, or would like clarification on anything, just let me know!