I didn't remove the alternator to put on my headers... I probably should have, but I was able to get a swivel ratchet in there.
As for the rest of the exhaust, I discontected the catalytic converter from the y-pipe, then discontected the y-pipe from both banks. I did support the cat. with a couple of 4x4 pieces.
My advice on removing the bracket is to leave it attatched. I don't see what you'd want to risk having something strip out if you don't absolutely need too.
Hope some of this helps.
~Eric