One big bit of advice if your trying to make the music a big part of the evening is to find a group of students willing to be in charge of it.
We gave the DJ at our prom a very rigid playlist, but he still managed to mess around with it. They feel they should be doing more than just putting a song on and then getting the next one ready.
If possible see if the venue will set up a computer for you, if they will its simply a case of queueing up the songs. You can even cut out the gap between songs by haveing the last 2 seconds of each song overlap, it's barely noticeable and stops awkward silences between songs.