#1
I got some gear sold, and bought a cab for $70, it's a Genz Benz GB115 bass cab, it's the normal black carpet thing with a metal grate and a white granite looking baffle. The back has two input, a sticker for a serial #, and a sticker that says Genz Benz 4 ohms. The guy I bought it from said he thought it was 8 ohms (selling it, but he was a keys guy), so I got the serial number and emailed Genz Benz, and told him and he said it was either of two cabs and both were 8 ohms, and that genz benz never had a 4 ohm 1x15. I bought this to run with another 8 ohm cab, but now I'm afraid of overloading my head.

TL;DR was genz benz bad about printing labels? Also are they good company?
#2
Open it up and see what impedance is printed on the back of the actual speakers--figure out the total impedance from there to be safe.

I don't have any personal experience with Genz Benz, so I can't help you there.
#3
I'll try, I'm not at home, but am I correct to assume I have to go in from the front of these cabs? cause the sides are all carpeted and solid.