Gandalf wrote:

I have to get some Advantage or Frontline (DUH..why didn't I think of
this already?) to give the cat before she can go to her new 'home'

How long does it take for Advantage, or Frontline to kill off all the
fleas this unfortunate kitty might have?

Because that's how long she will have to stay in my garage :-(

Supposedly, fleas die within 24 hours after treatment. I'm glad you found
someone to foster her, though. Even a closet has to be better than a hot
garage. Good luck!

kili