InGround SW Pool - winter operation

Winter operation for a 40k in ground pool with hot tub in-line. We closed the pool down last year and had a heck of a time getting the water balanced in the spring. After speaking with the previous owner, he told us the pool was setup with an automatic freeze detection system so we don't have to close it down and would be able to utilize the hot tub all year. My question is, do we need to (manually set) to have the pool water circulating all the time? And at what temperature should we leave the pool? Our temps have been in the low 20's at night, sometimes reaching 40's during the day.
And since there is only one or two of us crazy enough to utilize the hot tub in these temps :) how often should I be checking the chemicals & pH?

Sorry, not going to touch this.

I've seen pool/hot tub valve, piping and control set-ups that looked good . . . in a magazine. In real life, they've all been a mess. I could probably figure it out on site, but not via the Internet, especially when getting it wrong means major freeze damage!

Regarding chems: for your own safety, you need to check hot-tub levels before and after each use. People won't do that, which means hot-tubs are often unsafe, which is why I've never been willing to 'support' hot-tubs here.