Of course the whirlpool is winter-proof, it allows the water to circulate constantly. We have already used it at -10°C outside and it worked perfectly. Once it has reached its temperature, it doesn't need much electricity. The important thing is to always put the lid on after use and cover it with the tarpaulin. By the way, the idea is to use the whirlpool in winter....

Unfortunately no, not suitable for lower temperatures towards the 0 limit.

Yes and no. It is possible, but I don't think so, according to the manufacturer. Especially if the water in the pump freezes, the hoses or the plastic in general can burst.
Unless you let the heating run non-stop - but then it's a question of cost.