First off avoid Home Depot and STAY AWAY FROM WAYNE DALTON. The Home Depot Doors are a very very thin gauge steel. They are extremely flimsy and Wayne Dalton is just junk in general. I would call out a reputable door company and get some bids. Your doors are probably 8x7 ( heighth before width). The bids are going to be a bit higher but it is money well spent. Try to stick with a 24 gauge steel door and or 25 gauge is also exceptable.

As far as insulation goes you can get a vinyl back insulated door that will probably work just fine. If the garage is finished a two sided steel looks better in my opinion as well as offers better insulation, usually about 2 points higher on the R-Value, but they are more expensive.

Good luck

OOOOOOPPPPPPPPPSSSSSSSSSSSSS. I meant width before highth.