Ok, you’re asking too many different questions to which I don’t have answers for. The general consensus is that letters should be from recommenders that know you well enough to support your application (not just repeating your resume or grades; but specific examples of your intellectual curiosity in class, interest in chosen field, involvement outside of school etc.) and should be from a variety of fields (1 Humanities/Social Science + 1 STEM seems to be commonly required/recommended, w/a supplemental, if allowed, from a job manager, music or art teacher etc. who knows you well.)
Above all, YOU get to choose who to ask for letters, so do a self-judgement of your performance in the class and your conversations with the teacher (if they’re overly busy/show a lack of interest or outright state they write form letters, you likely don’t want a letter from this teacher.) You only have ONE guidance counselor, on the other hand, so don’t annoy them!
Some teachers/counselors will ask you to provide them with short answers, specific examples from class etc. so take the time to be thoughtful and through when you’re providing these. You want to make it easy for your recommender to write their letter.
While a bad letter won’t make or break your application, especially to selective colleges, you don’t want to make it easier for them to not consider your application further.
Students at private schools likely have more detailed recommendations than those at LARGE public schools, but this is more a function of counselor case load than anything else.
IMO always waive your rights to view your letters under FERPA. It’s especially important at selective colleges where they value the knowledge that the letter writer is frank and open with their opinions of you. However, even if you waive your letter-viewing rights, there’s nothing stopping you from viewing it if your recommender offers the opportunity (as some teachers will do.)
Also, you did not need to include the phrase “awkward immigrant mom’s kid,” just shy vs. more social kid for letters would have worked. As the child of immigrants myself, please don’t stereotype. 
Hope that helps! Good luck with admissions!