I have a pair of the 1st Gen ZipZaps.
I've never timed it but I'd have to guess 3~5 or so of run time.
Joints in hardwood floors would be just fine, but carpet is like mud! If you ain't going at full speed the car will pretty much stop moving.
Frequencies, 2

But... They changed them not too long ago. They now have analog steering (as apposed to the magnetic all the way left or right that they used to have).
And you can run 6 now I believe!
I can't imagine that the batterie life has improved much with the 2nd gen either so don't get your hopes up.
My opinion would be to get an xmod. They're probably like 8" or so if I had to guess, so alot bigger than a zipzap but still smaller than the usual RC car.