Sounds like you're going to have a nice setup there, Cleo.
I did the iPod/radio things on my old Jeep (CJ-7) a couple of years ago. Looked at the way Surfn's daughter is doing it, but the FM transmitter for the iPod wasn't quite there back then. Went with a Jensen radio that has an audio-in jack on the front. Nothing very fancy but it's definitely nice to have gigs of music when you want it.
Now I need to figure out what I'm going to do about speakers this time. I've gone through two sets in two years because it's really hard to keep them out of the weather down here when running with no top. There don't seem to be any waterproof speaker enclosures that still let good sound through. Most marine speakers I've heard don't sound very good either.