Don't know anything about your camera, but if you want the time and date automatically added when editing have a look at :-
http://dve.teletex.ru/en/dvrecdate.shtml
Failing that add the date manually as a subtitle when editing, at least that way you can remove it again when you want to. if you record it when you film it's there permanent and you can never get rid of it.
As far as I can see the only time you would want it permanently on the video would be for a security or legal dispute.