1st Time Magnum in the Shop-possible tranny problem

Ok, so last night i get a CEL, but a few weeks prior to that i noticed that occasionally i was leaking tranny fluid, more often after i was runing the a/c. So this morning, i' m leaving and and use the stick, what the hell, i get up to 2nd and it sticks. I cant get it in or out of 2nd. I drive about 5 miles like that then get home. I leave again and its fine, but the light is still on. SO i took it to the dealer a few minutes ago and explained the problem. I told them i was aware of the TSB for the o ring and the a/c water dripping etc. They agreed thats its a strong possibility that thats what it is. But, its friday, and their tech wont be back til tuesday.

Ok, no problem, i just want it fixed. we talk more, and i'm thinking if this is the problem, they change the o ring, fill it with fluid, and i'm back on the road right? WRONG! they said if that is the problem, they have to rebuild the tranny because of rust. That would take them over a week because of parts availability and a bunch of other crap.

Now i have some questions.

Is a rebuilt tranny just as good as a new tranny?

Can i ask for a new tranny?

Are loaner cars standard, this is my only car.

Have any of you had this problem, how did it go?