I'll take a gifted mortal, or one of the low-power spell casters in the city.  Nothing which would allow me to blow up a city block without significant planning (not a la Harry when he gets pissed and tends to slag things).

I haven't had many GM-spots (my first horrendous game is to blame) in my group since I'm mostly a player, but I will be GM-ing this RPG for sure.

Rules will probably be something along the lines of:
1) A preference of not highly powered characters.  Dresden has said that there are lots of lower powered people in the city, as is evident in WN - lots of dabblers with good intentions.
2) White Court/Order of St. Giles will be allowed with a VERY good back story.
3) Humans need an even BETTER back story than the Vamps.  they are not supposed to know in the first place.  It'll be like running a Call of C'thulhu game without a good back ground.
4) Group input on the characters.  I like some balance, but overlap can work well occasionally...

They'll probably evolve while we actually play the game and the players get a better grasp of the system.