well on #1 you only need to rejet when you make a change such as airbox removal or less restrictive exhaust because you are letting more air into the engine. With more air you need more fuel to prevent a lean condition that could possibly be damaging.

#2 The AI is the Air Injection. Its the tubes by the spark plugs. They inject air from the air box causeing the pipes to blue.(it's a pollutioin thing) So people remove it. You have to get the plugs for the head and a vacume cap for th intake and a block off for the air box. It's available as a kit at newspeedmaster.com

I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!