Catalina is the closest thing I could call a "home" airport. I grew up on Catalina and have flown in there many times. There are tie-downs, but as mentioned, bring your own rope is case none is available. Most parking is on the dirt, so just push into the spot and there won't be a problem. Right traffic for Runway 22 is the most common. Call 5miles out Monitor CTAF well in advance and request wind and traffic information. There is usually someone manning the radio to give you the runway in use.
It would be best to have a local pilot with you the first time in since that airport can take some getting used to. Runway 22 slopes up quite a bit so you have to over-rotate or you will hit hard since the runway comes up to meet you. The runway levels off at the midpoint, so it will look like you are about to run off the end, but you are only halfway. Quite a few pilots have tried to take back off after touching down (thinking they were out of runway) only to end up off the far end of the runway.
Watch out for windshear and downdraft off the approach end of 22. You are coming in over a cliff (much larger drop than Sedona airport - if you have been there), so windy days are interesting. I usually approach a little high and then use the required over-rotate/flare to bleed off the excess energy.
If you depart from 22, the taxi is downhill and takeoff is uphill so don't overheat your brakes and remember not to panic when it "looks" like you are out of runway on take off roll (probably not an issue in the RV). Watch out for Mt Orizaba to the south so depart straight out or downwind.
Taking off from Runway4 is a blast since it is downhill and the massive dropoff at the end of the runway. Good luck and be safe.
Edit: Of course it doesn't hurt, but you don't really need the raft. You can put yourself in gliding distance of the mainland or island if you cross with enough altitude. The best part of flying to Catalina is the view, so make a circuit around the island to check it out. Watch out for other aircraft flying through Two Harbors (towards the west end where it looks like Catalina splits into two islands). Also, don't fly into the canyons low, they are all blind.