Keep warm in Hokkaido

Hi. This question seem inappropriate as it is the start of summer.
But I would really love to know (especially those who stay in rural Hokkaido) to get ready for it since it is only less than 5 months away :)
How do you keep warm inside the house and on the street?

I try to control my electricity bills and I love to go outdoors. Is it true you sleep most of the time during winter in Hokkaido?

Which type of heater is effective for you? I don't quite agree with kerosene heater.
I have heard of people who use candles.

Which types of layering of clothes is most effective?

Thanks much :)