1- Add to that use only 1/4 turn shut off valves. They last longer, are easier to use, and you can see when they are off or on.

2- All tile should have the subflooring as prescribed in the TCNA handbook. For natural stone, you need at least 2 layers of plywood totalling 1.25" thick installed according to this article. There are a number of other factors for ceramic or porcelain tiles. For all things tile, head on over to the John Bridge Tile Forum where you can read the extensive library which has a section all about plywood. How exciting is that?

3- My local lumber yard, Clark's Hardwoods, right here in Houston will make custom millwork and ship it to you. All they need is a sample to work from. You may find a local yard to provide the same service.

4- Yes with lots of cussing and labor. Adding wine or beer may help reduce the cussing.

5- The bath contractor MUST address deflection so the joists can handle a tiled floor. The John Bridge Tile forum has a handy dandy deflecto-meter you can use to determine if your floors are up to tile or figure out what needs to be done so you can tile.

6- Somewhere on the John Bridge forum is a thread dedicated to what a homeowner (HO) should look for when shopping for a contractor.

7- Hire a company that does all the work in house, you'll save money and get a quicker job. Get a warranty with teeth in it. Don't pay up front. Get a freshly printed copy of their insurance.