After having many problems with writing and grammatical stuffs in the first semester, I joined a gramma course again and realised 'grammar' also means how to make sense of words...I just hope the ways of teaching English will be changed, at least simple but more realistic

I'm not a teacher. I wish to become a lecturer in university, but I can't since I do not own a master degree.
You can use both sentences, I think both of them are fine.

Hey, I think people is not a formal word at all. In formal cases, more specific words could be used such as the audience,residents,..based on individual case.

It would be easy to remember person -> people in plural. Persons or peoples are a little bit weird to me since I have never seen it in academic text except law(I believe law text has different way to express itself)