Ok i am a GM and running skulls and shackles and i gotta know... do the NPCS in the Adventure Path lvl on their own or do i have to keep track of their XP?
NPCs are normally static. They do not advance by default. The modules may designate specific ones advancing at specific points.
While playing in our S&S game, our GM only advanced an NPC if the party co-opted one to be with the party full time. Even then, they advanced only enough to survive in a non-attack role. So they usually were three or more levels behind the party and avoided combat as much as possible.
/cevah