What exactly needs to be cleaned off? If just mildew and general crud, wash it like washing your car. My favorite for cleaning is TSP, TriSodium Phosphate - you can get it at your local hardware store (wherever that might be, that big orange box store has it, over with the paints). It's a powder, mix it with water and go to town. Deep grime may require a power washer, easy enough to rent or borrow. A last washdown with paint thinner or mineral spirits (NOT acetone!) is good for final detail work. Mineral spirits in particular are really good for lifting bits of crud or adhesive off the surface, kind of lubricates them as you rub it off. And you may want a paint scraper, depending on what you're cleaning - plastic or metal scraper?, think it through.
If things are really, really ugly, you may want to consider sanding off a bit of the gelcoat with an orbital sander - start with 120 grit, don't press down too hard, just let the sander do the work. Go up to 600 grit, over even 1000 grit. Use fresh disks, you're only hurting your hull trying to "extend" a dull sanding disk. Estimate 2 disks per pass over the hull. A certain large online retailer from Seattle sells a nice assortment pack of sander disks, 240 up to 1000 grit, 10 disks of each grit, for 15-ish bucks. Don't sand thru the gelcoat! It's about a 1/4 inch thick (guess how I know?). Be extra careful at the keel. Anyway, sanding off the crud is only if it wont respond to less radical options.
Waxing... now you get into a real quandry. Are you going to race? If not, don't bother, IMHO. If you are trying to improve your times, wax is not necessarily the answer... As the parts of the boat where you're worried about water friction are - by definition - completely submerged, you actually don't want something that causes the water to bead, i.e. wax. You want something that causes the water to run in a nice sheet. Plenty of ppl want to sell you their "magic gunk." My suggestion? Forget that, get yourself a food-grade silicone lube spray (CRC makes one, $7-8 a can) and spray it on prior to your race. It will flake off pretty quick, but it's cheap and easy to apply. Why "food-grade"? Just my guilt at flaking silicone + god-knows what into the water. Silicone is no big deal, but I have no idea what they use as a carrier in the spray bottles from Auto-Zone. Just sayin'.....
Ok, there's my crazy ideas for a rainy Saturday. Best thing of all for hull cleaning and prep is, of course, elbow grease!