SUCCESS!! So the cam style stud remover wouldn't work; didn't fit between the stud and the dust cover on the rotor. Went back and picked up a set of socket style removers. The front stud was out already (pipe wrench) and the middle one seemed REALLY stuck, but got the rear one out. Put the attention back to the middle and last one, and it actually just shredded the entire layer off the stud, all threading gone. Crazy. BUT, started whacking it with the sledge again, got it loose, hammered a screwdriver under one end, then the other, and tapped up on the other side with the sledge while levering it up with the screwdriver. OFF!! Had to put the stud remover on top of it and smash it on with the sledge to get it to bite, but eventually got it off.
Mounted the new arm fairly easily on some new (used) studs that I picked up from my local 4x4 shop this morning. Good to go. But I think I have the actual arm in the wrong place, have to line that up better tomorrow. Also I'd had the caliper off and I'm getting a brake light and the pedal feels soft so having it turned up for a couple days must have gotten some air in the line somehow; not sure how... I'll try bleeding the line tomorrow and see if that takes care of it. Couple minor things and I'm ready for the trails this weekend! FINALLY!