As you probably already know, the Kerdi drain is available for either PVC or ABS piping, so selecting for your piping type is important. If you are confident that the 1 1/2" piping meets with any code applicable to your residence and also meets with your approval, then hookup requires a pipe that has OD of 2" piping and ID of 1 1/2" piping. Get a short piece, perhaps 12", of 1 1/2" PVC (your piping) pipe and a 1 1/2 coupling. Using the proper primer and cement, install the coupling on the pipe and let it set for a couple of days. Then take that assembly to a a machine shop to turn the OD of that coupling to the size of the OD of 2" pipe. Really quick and easy in a lathe. Now you have a pipe that will mate to the Kerdi drain and will mate to your present system. Part of the coupling projects past the pipe. Cut off any part of the coupling that is not needed for cementing to the Kerdi drain. Any clogs due to the stepdown will be right in the drain assembly, remove the grate and clear when and-as necessary.

Yes in my set up you would have to walk over to my temp valve. Maybe two will work best in your shower, or put the rain can closer to the controls. I think my middle temp valve is a temp control plus pressure balanced as well. It is most likely called a pressure balance valve vs a thermostatic valve sorry I think I mixed the terms up earlier. That means the water temp is always consistent to the setting. My water reaches the desired tempature within seconds of me turning my shower on in the morning and stays consistent if someone flushes or uses another water source else where in the house. Only negative is I can not have a shower colder than 70 degrees though... the three volume controls only control water volume not temp. My plumber advised me to buy one pressure balanced temp control and than the three separate volume controls. Most brands have matching lines for this set up. Here is an article that might explain it better. https://www.plumbingsupply.com/pressure-balance-vs-thermostatic-valves.html

seems like it could be a tough one since smell is subjective (although there's probably something out there that can measure smell) plus if more than 1 of u can smell it that'll help. I'm just thinking ahead if u need to file a complain with the licensing board. How long has it been since u texted him? was a good with texts before? i hope he's getting in touch with who he will and then get back to u but would be nice if he let u know he got your msg and will deal with it. I have a very sensitive nose so this problem would be a big one for me. I just got a bunch of air purifiers and have been learning more about pure air. your nose is telling u something. glad u r listening to your body

All systems will have standard 32x60 offset bases. The only one that will custom make the exact size and drain location would be USG. Usually shipped within a week. http://www.durockshowersystem.com/en/products/custom-shower-tray.html?utm_source=google&utm_medium=paid&utm_campaign=shower_systems_showertray