To understand these verses it's helpful to read them in context. I'm using the King James Version, which seems a bit easier to understand (in particular the part about "touching" Moses' feet).
EXODUS 4:22-26 (KJV) And thou shalt say unto Pharaoh, Thus saith the LORD,
Israel is my son, even my firstborn: And I say unto thee, Let my son
go, that he may serve me: and if thou refuse to let him go, behold, I
will slay thy son, even thy firstborn. And it came to pass by the way
in the inn, that the LORD met him, and sought to kill him. Then
Zipporah took a sharp stone, and cut off the foreskin of her son, and
cast it at his feet, and said, Surely a bloody husband art thou to me.
So he let him go: then she said, A bloody husband thou art, because of
the circumcision.
Moses was on his way to tell Pharaoh that this time, if he didn't let Israel go, he would slay Pharaoh's firstborn. On the way, the Lord met Moses (the firstborn of his mother and father) to take his life for not fulfilling His commandment to Abraham to circumcise every male. The statement "the LORD met Moses" may have been spiritual: perhaps Moses suddenly became very sick and Zipporah discerned the cause. At any rate, the LORD was there to take Moses' life. (Note that the KJV renders LORD in all caps when referring to Jehovah, {God Above Us}, and Lord when referring to Adonai, {God With Us}).
As the King James Version reads, Zipporah cast the foreskin at Moses' feet because she was a bit of a fireball (in the best sense), and wasn't too happy with Moses at the moment. "A bloody husband thou art, because of the circumcision!"
