Fuel - shall I be concerned if I don't drive much?

You’re probably fine.

How large is the gas tank? Now estimate how many gallons you might one in a normal month. Report.

I’d say that if you basically use about the equivalent of a tankful of gas within about 6 months then you probably have nothing to worry about.

Other than that a dose of Stabil per the equivalent of about a tank of gasoline won’t hurt anything, though I have gone to using SeaFoam as a fuel stabilizer and a few ounces of that twice a year to stabilize the fuel absolutely won’t hurt anything either.