How to enjoy bra shopping to the max?

I.
I have a few questions for all of my lovely ladies here concerning shopping for bras.  Feel free to answer all or selectively.
1) Does anyone have fun shopping for bras?  If so, what is your thought process?
2) If you were given the task of shopping with a teen/pre-teen getting their first bra, what would your big-sister advice be?
3) What is the best material for a bra to be made out of, in your opinion?
4) What qualities do you look for in a bra?
5) If you have big-ish boobs, how do you find a bra that holds it all together, but still lets you breathe? (This is one I struggle with.  Halp!)
6) Who is your favorite supplier of bras? Why?
7) Any advice for effectively shopping online?
8) Does anyone here go shopping for bras with dude-friends?  If so, if you were to provide etiquette advice for potential dude bra-buying buddies (try saying that five times really fast), what would you say?
9) I hope this next bit isn't disrespectful.  I ask only because I want to know how to be a better ally.  Does anyone have advice for bra/binder shopping for/with a bro who hasn't transitioned, or doesn't plan to transition?
10) Similarly to number 9, do you have any tips for how to make the bra-shopping experience more comfortable and enjoyable for our trans-lady friends?  Again, I just want to know how to be a better ally.
11) ... I will probably have more questions later after seeing the comments.  Thanks for responding!