[Vince]

In an NPC script you only have access to the callbacks and functions that are listed in a_npc.inc. Any other default sa-mp include (a_samp, a_objects, a_player, ...) may not be included. This means that you don't have access to things like IsPlayerAdmin, CreateObject, CreateVehicle, etc.

It is true that every NPC runs in its own process. Every time an NPC connects a new samp-npc process is started.