RE writers' rights: Yes, as far as I know, according to the WGA, the writers of movies for television should be sent the director's cut.
RE Tarzan music: As I recall, Charles Fox did an amusing score (on purpose, as it was a comedy-adventure) for TARZAN IN MANHATTAN, a CBS movie-of-the-week which was a backdoor pilot that never happened. Don't bother looking it up - it got relatively bad reviews. It wasn't horrible, it wasn't great. My only copy of the DVD is now in someone else's DVD library, so I can't listen to see if I'm right about the music. My favorite section of the score was a scene in which Cheetah is kindnapped by poachers and Tarzan goes to New York to find him - behind which you hear the usual action music - but if you listen carefully you realize that there is a male voice singing "Leave my monkey alone!"...
And, BTW, TZ IN MANHATTAN did sort of become a series - syndicated, not on CBS, and not set in NY. It was shot in Mexico. I co-produced (and wrote) it for a year, then bid a fond farewell. I like to watch Tarzan movies, but living with Tarzan 24/7 was not my thing. The series ran for a few years - played in Canada, too. Perhaps is on there, still. The Canadian DRs might know.