When I was still an aspiring writer (might return to that one day, right now I'm an aspiring startup dude) I used to do all my writing in coffee shops.

I find that the only way I can do anything creative is with a lot of noise around me, the randomer the better. Helps me focus and get into the flow for some reason.

Honestly, if there isn't enough noise I will often play three different pieces of music at once to create it.

As for b) and c) I never stayed at one place for more than a few hours.