as far as the carb. you will almost def have to rejet it. carbs don't usually come jetted for a particular bike, in fact your carb might not even have any jets in it at all depending on where you get it. either way, you'll most certainly want to jet the carb to your particular engine and altitude. elevation plays a huge role in jetting.
imo, the biggest most efficacious mod i've done was the port and polish. had kennedy_power do it and that is EASILY the single most effective mod i've done. his p&p and headwork gave me more juice than the airbox lid mod, the vforce3, filter, pipe whatever. p&p and headwork by someone who knows what they're doin will make an ENORMOUS boost in power.
of course all engine work on a 2stroke is founded on exhaust. you have to decide what you want out of your bike at the beginning and go from there.
if you ride trails mostly and want bottom end power more than top, then you need a pipe that will give you that, then have the p&p done to match the exhaust parameters. and headwork to compensate for anything lost.