There are 4 sections across the front mezz of the Imperial, house right to left, 1 through 4. Ergo 2 and 3 are the center sections. This doesn't mean that you can't see from 1 and 4, but the perspective is better.
There is a $49.50 discount out there for orch-fr mezz seats through the 23rd. I can't remember where however, but look around.
I would be fairly certain that there are some tix at TKTS at least until Christmas-New Years weeks. They might be rear mezz. I also think the very back of the house is cheap, $25-30.
The key point however is do not miss this play. I'd say it is the odds-on favorite for at least the Pulitzer.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher