The Orc rulebook says that once the nasty skulkers are revealed they follow he rules for characters in a unit, but does that mean that my TK with sword of anti-heroes gets +3S +3A?

this should probably be in the rules forum part.

i don't really know what kind of models you are talking about but it seems like you should get the extra S and A from the angle i see it.

probably not sorry
The sword only gives a bonus per independant character but the nasty skulkers are only treated as independent characters as far as where they are placed in a unit

Arnt they classed as unit champions? Basically if tey do then that sword wouldn't work.

Yeah, they don't count as Characters. So no synergy with the Sword of AH.