I'm sorta in the same situation.
All of the rubber seals around my slider have fallen off and I got the same answer from my dealer.
They told me the rear window is sold as one piece and there are no replacement parts for the slider or the window seals.
I'm trying to get an auto glass place to find some way to glue those suckers back on.
Regarding your window latch, I would see if you can buy that center piece of glass with the latch attached.