Compost Duck House/Water Heater?

It's getting chilly here in Western Maine and I am finalizing my plans for keeping the ducks warm through the winter, as well as keeping their water from freezing. Our 6 ducks have an insulated house that stands 3 feet off the ground. They also have the space under the house to hang out in during the day. This space is covered with hardware cloth on the 3 sides that stick out of the fenced area. I am thinking about putting a compost pile up to one side of the duck house and fence, using a doubled over tarp to keep the compost in & ducks out. What I am hoping is that this will heat the underneath area, as well as the floor of the upper area. We would close the other 3 bottom sides in, leaving a small door for them.

Since I would be starting this now, and temps are around 35-45F high and 20-25F low already, will it have time to heat up?

Will a 4x4x4 compost heap be big enough, or should I go up to 5x5x4?

Could I potentially run plastic tubing or drinking grade garden hose through the pile to keep water from freezing? Would it get too hot?

Could I attach it automatic waterer such as one of these: http://www.amazon.com/Little-Giant-Automatic-Fount-Waterer/dp/B000AYFZ60/ref=sr_1_3?ie=UTF8&qid=1383663455&sr=8-3&keywords=automatic+chicken+waterer http://www.amazon.com/Little-Giant-Automatic-Poultry-Waterer/dp/B00A7SG30G/ref=sr_1_1?ie=UTF8&qid=1383663455&sr=8-1&keywords=automatic+chicken+waterer

Any better ideas for a reservoir than an insulated 5 gal bucket with insulated cover mostly buried in the pile?

Thanks!
Aimee

I have never tried anything like this but ..... have you seen Pauls video on "500 Showers Heated from One Small Compost Pile " ? This might get you started :
http://www.youtube.com/watch?v=-Jm-c9B2_ew

Thank you Wayne, I had not seen that video and it was very informative & helpful