Will need water in home only 2 days a month during winter; is there any reason I shouldn't just turn off the water, to avoid possibility of flooding, while I'm away? Is there a problem with turning water off & on on that frequency? Thanks

I have been there, done that. $100,000 dollars damage. I turn the water of now when I go to the store. Just kidding about that, but a water leak can ruin you. So I opt for turning off the water for extended periods of absence.

What kind of heating system do you have?

Yes, I shut off my main even if gone for 3 days. Heat must remain ON and normally set no lower than 50 degrees if you have gas force hot air