Hi and welcome, Cooki1.
I'm not a kegger, so some wiser souls will probably contradict me completely, but my understanding is:
Cookie1 wrote:do I leave the beer in the fermenter the same amount of time as I would if putting it in a bottle?
Yes, don't keg it before the stage at which you would normally bottle.
Cookie1 wrote:or can I store it in a keg?
You can store it in the keg for quite some time, but don't look at the keg as a conditioning vessel. You can always rack the beer and cold condition in another fermenter before kegging.
Cookie1 wrote:Will it be ready to drink after being gassed or is there a longer waiting period?
It can be drunk straight away (again, this is my understanding so I'll sit back and wait for the howls!).
Cheers,
Oliver