there are two types...fixed and broken (ie single speed/freewheel/what ever)
As for the gearing...go with somthing in lower 60's you should be fine. Plus working at a high cadence is good for ya. Look at what it did for Lance Armstrong.
I'm in fort collins, not many hills in town, but at the foothills of the rockies. My gearing is at 78" for my main fixed gear. I also have another running at 85" for when i wanna fly down the street, sucks when somone pops out infront of me though(hard to stop)
check out http://sheldonbrown.com
You can find out all you really need to know from him. There is also a gear calculator, so you can find out what ratios yeild what gear inches.....ie my 78" comes from a 48:16 on 700mm wheels, and 172.5mm cranks blah blah blah...more than you prolly wanted.
hope this helped more than confused!
and remember if its not fixed its broken!!