Whether you use a kinetic impact puller or a collet, loosen the bullet first by seating it slightly deeper (maybe .010") into the case. They pull out much easier that way. Otherwise you can whack that hammer without budging the bullet if it's too tight in the case.
45acp FMJ have a pretty tough jacket. You'll pull them and resuse them just fine.
Remove the primer decapping rod and resize the case like normal, but you don't have to reprime. Just use the existing primer. Then bell, charge and seat like normal.
If you don't know what the old powder is, use it as garden fertilizer.