I don't think that you would have to keep them in the garage. I kept all my babies out in the winter time and it was cold. Now, they're fine. As long as you have something for them to get into that isn't drafty at night, they'll be fine. Its the drafts that bother them, not the in general cold temps.
The house that I have for my birds is a dog house that my dad built. The rooster doesn't actually have a house right now, thats coming soon.
You could always do what I did and get a dog kennel and use that. It worked great for a period of time, but it wasn't big enough when the chicks came and we had to expand.
Sometimes having chickens isn't about the eggs, its about the birds. I love my hen, she is a good girl, a good layer and a good mama. Shes also pretty friendly. The babies are much more friendly than they were a few weeks ago and not everyone has problems with their rooster like I do. Not all roosters are created equal. If I were you though, I would not get any roosters. If you want to hatch them, then wait for a hen to go broody and you can buy hatching eggs or an incubator with purchased hatching eggs. If you just have a flock of hens and you're around them all the time and go in their coop with them or hand raise them from chicks then you'll have really really sweet great birds. They'll figure out their own pecking order and they'll think you're their mama. haha.
There is nothing more gratifying than having your little babies eat out of your hand or sit in your lap. My hen will sit in my lap for upwards of 30 minutes and eat out of my hand. But you have to touch them and be with them a lot for them to be friendly.
Fencing is expensive and so are fence posts, that is one of the draw backs of building a coop. But once you get it done, then its done and you don't have to buy more. The feed is a little expensive too, but the prices are going down. Right now, I'm paying $17 for a 50 lb bag of chick starter/grower, down from $20 a few weeks ago. And then next week I'll have to buy a 50 lb bag of layer feed and thats like $18 or so, hopefully its cheaper since the prices are coming down.
And there is my chicken pep talk! haha.