No, the two pump bolts do not need to be loosened to remove the cover.
Yes, the gasket will likely be destroyed when pulling the cover off.
Yes, they are a bugger to get off sometimes. You might want to try CAREFULLY driving a chisel between the housing and the cover to wedge the cover off. The corners are tempting places to drive a chisel in, but be careful as the cast cover can crack if you get carried away.
As a tip for the future, what I like to do upon reassembly is drill and tap a couple of threaded holes around the perimeter so if I need to disassemble in the future, I can just install a couple of bolts to use as jacking screws. This technique also works very very well on the hydraulic housings as well.