1) how much is the z-grip worth by itself?
No idea of current value, sorry!
2) how much is it worth on a mid-90's automag with a powerfeed body and lvl7 bolt?
See #1
3) how do you set it up to work with the intellifeed thing and what kind of hopper would be necessary for that?
You need the appropriate microswitch...I believe it has a mounting hole in the grip, I can check later if nobody else knows.
4) is there anything I should ask the guy before buying it? Anything I should look for? (this will be my first automag)
See if it's been modified or if any of the threads have been stripped, especially the bottom line. I'm assuming its not the RT model with the banjo bolt in the back. See if it has "wings" on the top of the Z-grip. This may limit your choice of rails (Wings - classic rail only, No wings - RT or classic (you can also file them down))
5) would I, in the future, be able to put a tac-one body, x valve, and ULE trigger on it?
Yes, Yes, & Yes
