I swapped my pump out in the 94 while it was in the garage. Had the whole car setting up on jack stands and I used the hydraulic hack and a piece of wood to lower and raise the tank. Really wasn't that bad of a job. Just make sure the ring gasket is setting flat when the metal ring is put in place because if it has one little kink in it, it will leak gas from that kink. Been there and done that before when I bought the car. Use a flat head screw driver to knock the ring clockwise, until it's tight. Reconnect all hoses as you raise it back up in place. That's if you really want to see exactly what you're doing but it can be done by just lowering the passengers side down far enough to get to it.
If the tank is full, siphon gas into 5 gallon gas jugs until you have about a 1/4 tank or so and undo the passengers side strap, disconnect the hoses, including the loop hose in the middle and it will be low enough to swap. I have done it both ways. IIRC, it took me about an hour to hour 1/2 from start to finish. I wasn't trying to rush anything but noway in hell would I pay no $500+ to have one swapped out. I think you have a different issue and running the tank below 1/4 tank too much shouldn't have anything to do with not having power. It plugs in at the harness on top of the tank. I would check for voltage first, before removing the pump. If there is none, then find the cause for no voltage. Could be something simple that doesn't even require lowering the tank at all.
You keep mentioning the inertia switch. Did you press it back in to see if it was even tripped?
lol
But it's definitely not a job I'd pay someone to do. It' s not that difficult. It makes it a lot easier if the tank is empty though. 