Suggestions on how to house an outdoor kitty...

I have acquired a beautiful, loving, cat that I'm told is around a 3 year neutered male. He was left by a neighbor, we think, who probably thought the cat could 'take care of himself.' He is a longhair, with Maine Coone-like wisps flipping out of his ears, but he is very petite, unlike a Maine Coon. I noticed him around the neighborhood last year before the snow hit and then he lived under the shed in the snow and would run from me whenever I tried to get near. Finally, sometime in April, I saw him and he saw me and I made little 'happy cat' noises and he came to me. We have been best buds ever since. He had long strips of matted hair flopping around off his body and looked like a little prepared cornish game hen where there was no hair. I made a nest on the porch, and soon we went to the Vet and he got a clean bill of health, a shave and a bath. They said he was a great cat and I was lucky to have him, but I already knew that. Now it is getting cold and I want to buy an outdoor heated cat house for my little man. I named him, "Wegman," after the grocery store because he brings me things fresh from the fields. He brings in little parcels of meat, plays with them, then turns around and eats his dry food. Figures!
Any suggestions for outdoor houses? I already have 3 indoor cats and 2 big Labradors...I will try to take him inside, but have tried and he seems distressed while the other cats are wigging out. I would love to get one of those Cat Chalets but I want to make sure I can heat it, too, so his water doesn't freeze.

Any suggestions would be welcome,

Thanks,

Melissa