Need help getting my ducks ready for winter.

I have a Cayuga (hen) and a Welsh Harlequin (drake). And I need help getting them ready for winter. I live in Michigan so we get pretty cold winters. At the moment they are living in a pen and get locked up in a dog cage with a tarp over it at night.

I'm planning on buying a dog house off of cl for them and putting a piece of wood over the opening for a door at night and a ramp during the day time. And possibly a rubber flapped entrance/exit. But I was wondering if I should also get them a heat lamp for inside of the dog house? And will I have to insulate it or would a heat lamp work? And how many watts should I get? It will probably only be a 2x3 foot dog house since there is only two of them.

Also I have a pool for them and was planning on getting a heater for that, but I'm not sure if that will work because it's just a kiddie pool and made of plastic so I'm scared it will melt. Does anyone have any suggestion about what I should do with the pool?

Also will I need to shovel out the snow in their pen when it snows?

Sorry I know lots of question but it's my first winter with them and I want to make sure they are safe.

If anyone has any other advice for me please feel free to share.