Temp - not too hot, but a little hotter then warm - water cools fast.
I wash Charlie in the bathtub - its a lot easier as they can stand in the shallow part instead of the deeper.
Here's my basics:
1. Fill tub about 2-3 inches in depth.
2. Clip cats nails (all) and clean out ears.
3. Take a washcloth and wipe around the face and head (no soap).
4. Have shampoo and conditioner ready.
5. Warm 2 towels in the dryer.
6. Place cat in water. Have one person hold the cat still and then start using a washcloth to wet the cat down to the skin from neck down. Flip the fur backwards so you get him all wet.
7. Use a little shampoo (either good quality cat shampoo or something like Pantane, Nexxus human shampoo) and start soaping the cat and rubbing it in. If you use peopel shampoo you will have to use a conditioner after washing out the shampoo.
8. I use a hand held shower head for rinsing - its works well. Drain the tub while rinsing the cat. After the shampoo is rinsed out, put a little conditioner on the coat (top, sides mainly). Then let it sit a minute or two and rinse that out.
Be sure to rinse ALL shampoo/conditioner out of the coat - then rinse once more. I use a vinegar rinse on Charlie that really gets out the shampoo - its 2-3 tablespoons of vinegar to on gallon of warm water.
Wring the cat out by squeezing as much water as you can from the coat (that's why you need 2 towels). Quickly wrap the cat in a warm towel and start rubbing dry. When the first towel is too wet, switch to the 2nd one.
If shorthair, you can smooth down the coat and put the cat in a room with no drafts to finish drying. If longhair you will need to comb and blow dry so the coat doesn't tangle. Also if longhair you need to comb all tangles/knots out of the coat before you put the cat in the water.
As far as how often, that depends. You can safely wash the cat every other month or a few times a year if you don't show. Charlie gets a bath before every show. Usually once a month, sometimes twice depending on when the shows are