why would you want kuemper to be a backup, or domi back at all

Not touching Domi or Ghostisbehere.

Why trade for Johansen if it's to buy him out?
There's no way we take a 2.66m hit on the cap for the next 8 years!
With players like Suzuki, Caufield, Romanov, etc to resign in a couple of years, that dead cap will cause too many issues.

I wouldn't give a 1st for negociating rights. He's that's the price once Hamilton is signed, maybe, but not just to get the chance to work on a contract without guarantee he's signing.