Since Mike hasn't answered this one yet, I'll answer it.

I'm guessing that the rule you're referencing is ASA. Answer to your question(s):

Leaving the box refers to one foot (or both feet) COMPLETELY outside the box DURING the pitch. (Think of rule about contacting ball while foot is outside box).

This rule basically came about because of the SP big boys who would start in the box, then go back BEHIND the box, and then get a running start to contact the ball.

In your scenarios, if there is no pitch yet, then you would let all action continue and call the pitch (and if I'm blue, it's gonna be a strike call ). Now, if the pitch has already been thrown, and the batter steps out of the box, then returns to contact the ball, then you have an OUT.

Hope this clarifies.

Serg