Welcome to the forums wingnut!!!
I have never taken that much time off so it is tough for me to guess how long it might take you. I bet if you get back into it you would be suprised hwo well you might be playing in a month from now if you get out a few times per week.
The one thing you have to do to start is to keep everything simple. No aiming for the lines, no fancy shots, just work on getting your timing and your strokes back.
In terms of getting back in to shape, I guess that depends on how long you let yourself go and how bad it got. Need to shed 15-20 pounds, might not take a long as you think with a good diet and some good tennis. I would get out and do some runnign as well. Get your legs use to that abuse again, ecause tennis will take it's toll.
I would do a lot of stretching as well. No need to hurt yourself right off the bat.
Welcome back to the game!!!