when changing flanges to unstake the companion nut do i jsut use a punch?

also should i replace the companion nut after every removal of it? or can i just restake it once its on and it'll be fine?

Punch, screwdriver, whatever ya got laying around that will get in there. Once it's opened up a bit, cranking on the nut will finish the job.

You're *supposed* to get new nuts, but I've reused them just fine. Sometimes it hard to re-stake the tab (cause you probably beat it up unstaking it), so locktite is your friend.