I am going through the same process as you.

Where is the "faucet rating link?"

http://starcraftcustombuilders.com/sources.faucets2.htm

If you're not going to have the fixed and handheld showerheads at different temperatures at the same time, you can get by with one thermostatic control. If you are going to have both showerheads running at the same time, you'll probably want a 3/4" valve. You'll need two volume control valves, one for the fixed and one for the handheld. You'll need a wall pipe for the fixed showerhead and a wall union for the handheld. If you want to vary the handheld height, you'll need a slider bar. You'll also need a hose for the handheld.

Moen has spa sets that contain just about everything that you want, except that the fixed showerhead is a rainshower. The spa set may or may not include a slider bar. They're more than twice what you want to spend, though.

We got a Moen fixed shower head as well as a Moen hand shower on a slide bar in chrome and have been very happy with them. Both form and function are perfect. The shower head is the Castleby Four Function Shower head, the hand held is Moen 4 function Massaging Hand Held Shower #3867. I ordered them through Faucet Depot, and was impressed with the service. It is confusing if you don't know what your doing, so I told the girl on the line what I wanted to accomplish and she told me what parts I needed. When I got the order it was perfect. I thought the prices were reasonable too. One reason I wanted to go with Moen is because I've heard that their warranty program is one of the best.

Suggestions on a good brand of thermostatic control valve?

My current master bath has three shower heads (Kohler) that I am probably going to reuse. They are very heavy and we both like the spray pattern. However, since we are retiling, I think it's a good idea to replace the thermostatic control. It is American Standard and 15 years old.

I suggest you visit your local plumbing showroom. After months of searching online and in catalogs and being slightly confused, I finally walked in a showroom today. An organized and experienced clerk had me outfitted for a whole house which matched my budget and wish list, except for a few items I had wanted that she was going to have to research. Time spent? 45 minutes.

Check out Terry Love Plumbing Forum. There are alot of plumbers that frequent there and offer free advice. It was a tremendous help for me in my search.