What powerlevel did you start your campaigns at?
7 refresh, although I bumped to 8 refresh after 6 sessions.
What city did you use for your campaign?
No city. The PCs are a biker gang, and so we use overarching campaign themes rather than location-based ones, plus many of the faces are nemeses of individual PCs and they typically have reach long enough to threaten the guys wherever they might be.
Did you have any special requirements regarding the characters in your campaign?
Monster-hunting bikers. Mortals, spellcasters, and holy-based characters would be the easiest to fit in, but as long as you explain why the other gang members haven't hunted and killed you, you could play a "monster" character, that's fine.
How close are you following the timeline in the books?
Not at all. We're not really even in what I would consider the Dresdenverse. We just steal from the bestiary (a lot) and cosmology (a little). In fact, starting our next session I'm converting the campaign over to Fate Core and doing a more focused ruleset now that we've been in nearly 10 sessions. We know generally who everyone is, what we like to play, and what we like to do in the campaign and so I can tweak rules to promote those things now.