Height of the rainshower head? I'd bring it down no lower than about 12" above the height of the tallest user. It can be a bit lower, but try to stay at least 8" above the top of the tallest user's head. Depending on the style of head you're using, 18" to 24" extension will work fine. Most true rainshower heads will not perform well unless they are installed parallel to the floor. So installing them on an angle, as they might be when coming out of a wall? You'll get some "rain" and some "dribble". There are hybrid rainshower heads that are designed to replace a standard head coming out of a wall, but they're not true rainshower heads. They usually have fewer holes to give a more forceful spray. They are "in between" heads. I've not heard of cleaning problems with metal hoses. I suppose hard water could bring that into play. I do recommend getting a hose long enough so that you can use the head to wash down all surfaces in the shower. You can also get additional head hanging brackets, they're only a few dollars each, so you can mount a bracket to hold the head at knee height for shaving legs, etc. Metal versus plastic? Some metal heads are cheesey, some plastic heads are fabulous. I've showered in all types of settings, from razor sprays that are painful to the gentlest of rainshowers. From one shower head to full-blown 24 head spa setups that make you feel like you're in a car wash. When I built my own shower, there were no limitations. My wife had carte blanche, we had no budget. All we did was we put in two heads on two valves. A 12" overhead rainshower, it was about $100 for the head. On the wall I installed a Grohe Top4 Relaxa head on a vertical wall bracket. I'm 6'4", my wife is 5'1". The head is easy to slide up and down as required. It can also be taken off the clip to be used as a hand held. I installed another bracket lower on the wall for my wife to use when shaving her legs. She can sit on a teak bench and clip the Top4 head into that bracket while she does that. I have two separate on/off supply valves, one for the overhad and one for the handheld. They can be run independently or simultaneously. They are simple valves, Temptrol. It's an excellent valve that will never cause problems. $100 for the rainhead, I think it was around $175-$200 for the entire Grohe setup, the Top4 head, the bar, the extra long hose, etc, about $200 for the two Temptrol valves. $500 for the whole shebang. No regrets. In a tub/shower combo, a rainshower head could be brought to the ceiling. There are plumbing kits that have chromed or other finish tubing that can be surface mounted on the wall to bring the water to an overhead rainhead. But mounting a rainshower head on a typical angled arm coming out of the wall? You might not get good water flow out of that. I have installed in-the-wall plumbing so that a rainshower head could come out of the ceiling in a standard tub/shower surround. The setups have had the standard wall tub filler and wall shower valve setup, I've usually installed a diverter valve so the water could come out of the wall shower head or the overhead rainshower head. Nothing ghastly about that at all. I would not have just a rainshower head as your only head. As other have mentioned, it's a very gentle flow of water, and does not do a good job of penetrating hair to rinse out shampoo. Mongo

Glad the threads you read were of help. Easiest, and often times the most user-friendly, is two supply valves, one for each head. With two bathers, each can select their own water temp. In general, that can be achieved most economically by using two two pressure balance valves at an economical price. Diverter valves and their trim can often be as expensive as a supply valve and its trim. Obviously you can price things out through the manufacturer of your choice: -Two individual supply valves and their trim. -A single supply valve and its trim plus a diverter and its trim. When you get into diverters, then you have all sorts of choices...the diverter can supply one head OR the other, but NOT BOTH simultaneously...OR it can supply one head OR the other, as well as BOTH simultaneously. As you wrote, with a PB valve you may not get temperature control at any volume. Volume control at any water temp can be of value, it depends on how you use your shower. To do that, you're right, it can be accomplished with a thermostatic valve. To be fair, there are some PB valve that offer that as well, you'd have to shop around to find one. But for the most part, PB valves at low flow will only give you cold water. My own shower, we have two PB valves that supply two individual heads. I do like the ability to have different water temps out of the two different heads. You're certainly on the right track. It's simply a matter now of balancing features versus budget, etc.

I don't see why you couldn't connect your hose directly to the shower arm without a diverter. I think the connections are all pretty standard. Shower arm, shower head, shower hose, and diverter all use the same screw in type connection. Use a good teflon tape (I like the thicker ones, not the thin white ones) and it should be water tight. Watch a youtube video on how to wrap the teflon tape to be sure you go in the right direction. If there is a rubber washer some times you don't need the teflon tape. You might just want to get a longer shower hose. This one is 8ft. 8 ft shower hose They make them even longer. Longer shower hose If you need the whole assembly, this one comes with the 8 ft shower hose. We buy this set-up and then put our own rainfall shower head on it but since you don't need the shower head you could just use the wand with the diverter always set to the hose. It has 3 pressure settings. We use the highest pressure for washing our dogs and the extra hose length comes in handy. It also provides a nice spa like experience for muscle massage. waterpik with hand held

Depends. If you are going to use it just for rinsing off the walls and glass, then just about anywhere as long as the hose is long enough. I don't have had stationary shower head, only a hand-held on a slide bar. Since my shower is 32 x 32 it is positioned near the hinge side of the glass door so it can rotate the spray into the shower. Standing diagonally in the small shower gives me a bit more room. A slide bar allows you to move the hand-held down a bit and shower without getting your hair wet.