This site has been a great resource and has helped me with my Stenner installation, so I figured I'd pay it forward. Following is all the information I have collected reading though mult threads.
I ordered the 45MPHP10 and the Stenner 15gallon grey tank. You don't need the high pressure pump...but I'd figure better safe than sorry. The fixed rate pump seems to be less maintence than the variable rate ones, hence my decision to go with fixed rate. 3gallon per day would also have sufficed, but I'd rather run the pump for a shorter period of time/day..plus have the option to shock the pool using the pump as well. FYI the only difference between the 3gal/day and 10gal/day pumps is the tube it comes with....which can easily be changed. The Stenner tank is more expensive and you can get other tanks for cheaper....but the cleanliness of the install is worth it for me.
As far as control of the pump, as suggested before in other threads....the preference is to have the Stenner pump on the same timer as the filter pump. That way you minimize the risk of having the Stenner run while the filter pump is off. My current pump is 240v running off an intermatic T104. So I decided to go with the intermatic P1353ME. Notes on wiring: P1353ME can be used with both 120v and 240v loads. In it's typical installation the P1353ME will only switch off 1 of the legs on a 240V load. Which means there is still a hot 120V source going to the pump when it is off. This can be done, and is ok, but not preferred. BUT you can wire the P1353ME so that it switches off both legs of the 240v pump/load....by wiring it and setting it up on MODE 5. In MODE 5, Circuits 1 and 2 are now both controlled as one circuit. So when. You turn off circuit 1, circuit 2 is turned off as well. However it limits you to controlling 2 separate circuits/loads, instead of the 3. The second switch is wired to a GFCI outlet that I'm going to plug the Stenner pump into. I'm fine with that since I only needed to power my pool pump and the Stenner pump.
I ordered my Stenner pump and tank from Lockwell...which had a better price than USwatersystems. Lockwell seems to be slow in processing my order. Site said it was in stock...but when I inquired 3-4 days later I was told it was being shipped to them from the Manufacturer and then will ship out to me. I only got a "processing" email the day I called them. I have a feeling my order was sitting there and missed until I actually called. I'm still waiting for the pump to arrive...and will work on the plumbing once the tank and pump come in. Plans are to remove my inline chlorinator and put in the 1 1/2" X 1 1/2" X 1/2" Tee instead of drilling and tapping. I have a 1/2" plug in case I want to remove the Stenner pump.
Here are some pics of the wiring. Will update once I get the tank and pump and have that installed.