anti seize will do fine, as long as you use the recomended torque spec.s the nuts/bolts wont back out, you are recomended to re torque exh. studs after getting engine to op temp, the lock tite would be bad, due to the heating and cooling, like you stated, there going to be a pain to get off next time anyway, and on the spring bolts your right again, that is a flex point that compensates for the engine torqueing and twising, from cat back is suposed to remain relatively still but the header is distributing the torque to the cat and without those springs it could crack or break the header to cat flange. fyi.. i have an aftermarket high flow cat that is a little shorter than stock(1/8" shorter) and i had to tighten the crap out of it to pull the gap together which in turn collapsaed the springs, in turn while i was pulling my motor out for swap last week i found the rear braket for header(beside oil filter) was cracked, possibly from our little spring discusion