How to replace fuel tank on 1100evo?

I had a spinning tank bolt on the rear mount of my 2012 1100evo. I read several places where people recommended drilling from the top side and replacing the captured female insert in the tank's rear mounting tang with just a hole to allow passing through a bolt from the top side and securing with a nut from underneath. Well, that's bad advice, or at least not true on all models/all markets. Mine has a hollow tang and gas extends all the way back into the mounting tang area. The gas drips on the floor from the pilot hole I drilled say so. So now I'm on to replacing my tank.

Question is really a couple of things.
1) to swap fuel pump over, what is involved? Replacement fuel pump gasket? Any tips on torque specs, things to watch for in a plastic tank replacement?
2) almost every used tank I see for sale has the keyed gas cap still in place and notes 'does not come with key'. How does one remove a cap that doesn't have a key and swap on the existing cap so it matches existing ignition? The only mounting bolts I see are inside the filler opening once key has given access, and I SURE don't want to damage a newly purchased replacement tank trying to force open an old cap without key.