3rd Strike Bunt
 

Youth league, ISF fastpitch rules. Batter bunts with a two strike count. Ball goes straight down and hits the batter's leg in the batter's box and goes foul. How would you call it if (a) touches the batter in fair territory, or (b) hits the batter in foul territory, before going foul?

I don't call ISF, but in USSSA and FED, in both of your situations I have "Dead Ball, Batter is out". If the bunt hits the batter in fair territory (outside of the boundaries of the batter's box), this is dead ball, runners return to the last base touched. If the bunt hits the batter in the batter's box, this is again dead ball, and because the bunt attempt with two strikes wasn't a "fair ball", the batter is out. In both situations the batter is out, but for different reasons.

Sorry. Better to Read the Book
 

ISF 1:37.e
Sec. 37. FOUL BALL.
A foul ball is a legally batted ball which:
e. Touches the batter or the bat in the batter’s hand(s) a second time while the batter is within the batter's box.
i.e. Batter is out, bunting foul on 3rd strike.

Blackie,

A batted ball can't first hit the batter and then go foul.

The ball is dead the instant that it touches the batter. It can't go anywhere, either fair or foul, after that point! ;)