J,
You do not need a check valve between the SWCG and the heater. That check valve is only required if you have a tab feeder.
I have three saltwater pools and do not have a by-pass or dummy cell. I can't think of any reason to have them.
In the winter you just set the output to zero. In my case I have separate circuit breaker for the SWCG power supply, so I just shut it off in the winter. This is not the same as the small grey breaker that you never want to try to turn off.
I would not add any salt until the water temp gets about 55 degrees on constant basis.
Your pool most likely has a lot of salt in it right now. I recommend you get a Taylor K-1766 salt test kit. You need to have the ability to measure the "actual" salt level vs. what the cell reports, which can be way off.
Pool math will tell you how much salt to add. You enter what your pool currently has, and pool volume, what your salt target is, and it will tell you how much more you need.
CYA of 60 is fine in the winter. I would not worry about getting it up to 70 until the summertime.
You might want to post a couple of pics of your install wiring before firing it up..
Edit.. You will need to tell ScreenLogic you have a SWCG so that it shows the following page..
View media item 1963
Thanks,
Jim R.