Hopefully a wall directly behind this faucet wall will have an access of some sort to get at the piping. If your house is 50 yrs. old, you will probably have galvanized pipe. If the shower is on the first floor, it would probably be wise to change the piping from the cellar up to this fixture with copper because you will probably end up having to use some copper in the change over. One of the major companies (either Delta or Moen) makes a large plate that will fit over a hole that you would have to make to change the faucet from the tub side. The company that makes the plate has a faucet that fits perfectly into this plate. The Moen plate is called a "remodeling cover plate" and the part # should be #1920. I don't have a Delta number. Even with this, you have to be careful and not make a hole any larger than the plate will cover up. If you have ceramic tile on the shower walls, then the job gets even trickier. It would probably be a whole lot easier if you could do most of the work from the backside.

I've seen a bathtub set up the way you want. It had a standard tub faucet down low to service the tub (and in your case you could add a hand shower diverter), and a second faucet set up high to service the shower head. The upper one wouldn't need a diverter, as it would feed straight to the shower head, just like in a shower-only stall. This should be fairly simple to plumb since the wall will be open anyway. The concerns I would have would be if your code authority would want you to use larger water pipes because there are two sets of fixtures. They might also, or instead, want a larger size drain. I wouldn't think these would be required, but, you jurisdiction/inspector might vary. An additional option for you on the lower filler would be to use a standard 3 handle valve set (middle being the diverter valve) and instead of sending the output to an upper shower it just go to a stubbed out pipe where you could attach the handshower.

Moen, curved rod, screw-in. $32 at BB&B. I redid my hall bath last summer. I developed a terrible aversion to having holes drilled into my new tile. The thought of it made me ill. I bought a straight Moen tension rod and convinced myself it would be just as good. I wasn't convinced it wouldn't fall down and the amount of room in the shower was just kind of meh. I bought the curved rod and figured out its sweet spot for 1) inside the shower, 2) how it would hang outside, and 3) where to drill. It is divine. It looks good and the inside of the shower feels way roomier than those extra couple of inches. As far as I know, we just used anchors (didn't screw into wood). I only use one lightweight fabric curtain so there's no undue weight. It's an awesome innovation.

Well, 3-230C is for cold water and 3-230H is for hot water, so they are not what you want. I am going to bet that 3-230 and 3-230B have some clear difference such as one is for a 1.2" supply pipe and one is for a 3/4" water supply pipe. If you look at the further details, look for the one thing that they do not have in common and you will figure out the difference. Do you know if you have 1/2" or 1/4" water supply pipes going into the shower? The 3-1003-TR is a thermostatic valve and diverter in the same circle base, for a 1/2" water supply line. To see if it fits, go measure the distance between the center of the two pipes sticking out of your wall and see if that matches the measurement in the catalog description. You may have to look at the specification sheet. It sounds like you may not know what kind of shower you have. Either it is a thermostatic valve with a separate on/off valve. In this kind, the temperature (thermostatic) valve is set at the temperature you want and never has to move between showers (unless someone who likes a different temperature showers between your showers). You turn on the on/off valve only, and can control the volume to any strength between off and full. OR, you have a pressure-balanced shower control where you turn it on and as you get it further to the right, it gets hotter and stronger. You can't control the strength of the shower water, except by turning the hot/cold control. The second piece coming out of the wall directs the place the water is supposed to go. It could be to a bathtub filler or to a shower head or to a second shower head, or to body sprays. Some control two things only, others control three. If you are not in California, some will let you turn on two at the same time. With the builder telling you to get the diverter and valve, it sounds to me like you have a pressure-balance VALVE and need a DIVERTER to direct the water to one of two or three functions (shower head, tub filler...). But maybe not! You cannot be sure if you do not know what those valves sticking out of the wall are for. Are they 1/2" water supply or 3/4"? Is it a thermostatic valve or a pressure-balance valve? Is the other one a diverter to chose between tub and shower functions, or is it an on and off and volume valve for one shower head? Both of the valves you are showing are for thermostatic valves. Neither are for pressure-balance, so that is why the instructions to get a valve and diverter are confusing me. By now, your builder will be back tomorrow, so all this is moot. But I thought I would try to give you a primer on the different kinds of shower controls so you would know more when you talk to him. Your other option is to go read the boxes of the Newport valves that are in your walls. Is there a box the builder throws things in to be seen in the work area? Look for the boxes the valves in your walls came out of and read their part numbers. Then go pull them up on the search box on the website and see what kind they are.