1997 Chevy Suburban fuel pump, radiator

My husband and I are having a few problems with or suburban (truck). First it was the radiator. The temp. Gauge will flux. Between under 180 and 1/2 above 210. When it goes beyond 210 we loose heat in the cab. It's loosing fluid but we can't find leak. It smells outside but not in the cab. 1st question: What is the likely problem? Note: it does have rear A/C.
2nd: I drove the kids to school. Came home and backed up into the drive which has an incline (back end higher then front). My husband went out later to work on the radiator. He turned the truck around (now front end higher), put fluid in the radiator, tried to start it but it wouldn't. It turns over but doesn't start. The engine sounds normal when we turn the key but it just won't run. He checked the fuses - nothing. He thought it might be the wiring and fuel pump. We moved it into the garage (level surface) so he could check the wiring underneath. Later he told me that he had it going a couple of times but wouldn't stay running. He now is attempting to take off the fuel tank to check the fuel pump but it won't release. He removed two "straps" but it still won't release.
Question 1: are we on the right track with the wiring/fuel pump?
2: is there something else holding up the tank?