Since I have a trek 1000 that I use for commuting I can answer some of the questions from Jarery.

I can fit fenders front and back, SKS P35.
With fenders the largest tires will likely be 23-622, maybe 25-622.
A rack can easily be mounted on the back. All the eylets are present.
I don't know what is appropriate gearing for the OP.
Chainstays are 41.7cm. I can mount panniers and not suffer from heel rub but my feet aren't too big, size 42.