Should I make sure recommendation letters go directly and ONLY to Common App? or is it ok if I receive them myself?

Answered

if all of your schools are Common App (or on a similar platform like the Coalition App), then you should just send them through the Common App. it should be the easiest and fastest way to do it.

if your recommenders would rather send them to you to upload, that's fine in general, but you need to MAKE SURE that you waived your right to view the letters on any application that you're filling out, and that your recommenders are sending them to you voluntarily. there will be a section on every application that says "do you waive your FERPA rights" or something similar, and you should always say yes no matter what. if you don't waive that right, colleges are going to think that the letters aren't authentic because your recommenders knew you would be reading them, and that can actually have a huge effect on your results.