Probably a safety issue considering the screen is in the front. I doubt it (although I don't know) that you can watch while driving, refer to your manual.
Yes, you can. But No, it's not legal. Unless the mustang set-up is different from most other cars it's actually pretty easy. I don't recomend doing this though as it will open you up to a lot of liability if you get in a wreck with this on.
For Kids I would recommend some headrest monitors. They are cheap these days and will be legal and probally even more enjoyable for your kids
-BUT-
Basically all that is needed is to ground the line that is the switch for the monitor function. 9 times out of 10 they run off the e-brake switch.
yeah, we have those dual monitors for the family volvo wagon, just didnt want to be cluttering up a muscle car like that. I knew it was illegal but thought maybe there was a way around it. Thanks for the input.