First I hope you get your boat. I bought a paddlecat last July and it has been a great boat. I just got back from a month long trip to Costa Rica where we brought the boat down and paddled it. It was a great verstile boat and light enought to check through the airlines without additional fees.
As far a river gear goes remember that you stay a lot drier in a raft than a kayak. Definatly something for the feet is key. Cold feet can ruin a day. Past that I think something to keep dry is important but I find that when I put on a bunch of layers under a dry top it is just big and bulky. Splash pants are great but often times in a raft river shorts with a layer of neoprine will work (at least for me).
Remember it is always good to dress to swim