Yes, heating pads are available for kennels, though the need for one is up to you. Sheperds are indeed able to handle the cold, provided they can remain dry and have a place out of the wind....which in the garage won't be a problem. That is where our dogs stay, but they do come in to sleep at night. More because my wife wants to have them inside than any need to keep them in.

The consistent 2 hr trips outside for "potty" will work in time. One thing we have learned is to take the pup to the same place every time you go out and speak the same words, like "Go Potty". When you put the pup down on the ground to do its business, if it attempts to get up and walk away, grab it and put it back down and repeat your potty words. If after a few attempts still no potty, go back in side and try again in a bit. Pretty soon, all you'll have to do is say the potty words and if he has to go, he'll beat you to the back door. Of course if he does potty, praise - praise - praise.