Divernva,
Catalina Divers Supply is a good ops to go with (only 2 to choose from on the island, hehe), John and Mark are good guys and the rest of the crew in the trailer at Casino Point are very helpful as well.
Ahhh, the Atwater, very diver friendly and inexpensive compared to other hotels. They are a block or so from the "beach" but you will have a nice little walk to the Point. It is close to the green pier though and that is where you will catch the boat for your boat dive. The Atwater does not have elevators so be prepared to climb the stairs. The rooms are on the 2nd and 3rd floor. I always carried my gear bag and suited up at the point. They also have lockers at the Point that you can leave gear in overnight (not my reg and computer though):nono:
As far as rinsing gear, there is a restroom with showers I believe right across from the Tuna Club that you can rinse down the gear.
Also, when you get off the "ferry" there is a shuttle service that will store your gear there at the dock and they also will transport your gear to the Point (I believe it is around $8 per bag though for this service. I have never used them myself personally (too cheap).
Anyway, you will enjoy. If you have never been in kelp be prepared, it is the most amazing dive you will have. There are some "wrecks" in the Point that if you ask the guys in the trailer they can give you more info on. The wrecks are in about 60 to 70 fsw (mainly small sailboats). The 2 giant sea bass are still hanging around, hopefully they will be there the end of August. Bring your u/w camera or you can rent (or buy a disposable from CDS) to capture the moment.
I am going to be there on 8/5 and again 8/25 and 8/26. Don't know if I can get away from work in the middle of the week but if you need a dive buddy and I can get away for a day I will dive with you.