"A reading of the NT can show one that A there is no recommendation to stop the old practices and B absolutely no reason to stop following the Law. In fact that was one of the central themes of the message."

I don't mean to be argumentative, but I remember a number of books in the New Testament discussing this very issue. Jesus routinely broke or challenged elements of the Law at least as it was being practiced at the time. Paul, another rabbi, speaks at length about the why Christians should move away from the the Law and eventually convinced Peter and other members of the early church to stop requiring cicumcisions or kosher dietary practices. I also seem to remember that Paul had considerable help changing Peter's mind on this from no less than the resurrected Jesus.

I do think the discussion of Passover transitioning into communion in Christianity makes sense, though I've never really seen much written on it. Passover celebrates the deliverance of the Children of Israel from slavery, communion the deliverance from sin.