Live rock and live sand... Yes. I actually would be against any setup that does not contain live rock, unless it's a quarantine setup. Live sand is good, although not necessary. Many people actually run their tanks without any kind of sand at all. If you have live rock and "dead" sand in your tank, the "dead" sand will eventually become just as live, possibly lively-er than live sand. Live sand is probably best used just to introduce more critters, not as the whole of your substrate.
The percs... great beginner fish. Easy to care for, it along with damsels is one of the first marines to be supported in captivity. Usually leave all other fish alone, except for, well at least sometimes and IME, other damsels/clowns/chromis. No, you do not have to introduce other fish at the same time. The only thing I would warn about with these guys is they are susceptible to clown fish disease (Brooklynella hostills), which, IME and from what I've read, can take down a clown in 24 hours, they also IME don't show any signs other than a bit of a change in colouration, well at least not before it's too late.
How big a tank are you planning on here?