I've got an 8.5' x 16' trailer. Gotta be careful with a 9 ft door.
For "residential" garages I always go with an 8' door height. Modern trucks "barely" fit in a 7' high door. My '81 Toyota wouldn't go in a 7' high garage entry after a lift and 35" tires.
For "shop" doors, 10' wide minimum. If you've got the height, with a 14' high door, if it goes down the road, it goes in the shop...
Roll up doors ****. Biggest mistake I made on the shop.
IMHO, spray foam is the best insulation you can buy. Around here, it's a swing of about 300% over traditional bat insulation. My home has a standard vapor barrier on the outside and spray foam inside the walls. Your attic becomes heated/cooled space with spray foam, big advantage if your air handler is in the attic.
My shop (steel) has no vapor barrier, straight spray foam to walls and roof. Mini-splits for heat/cooling.
Closed cell is much more dense, more expensive. You use it where you have limited space. Otherwise use open cell.
There are great "hybrid" insulation solutions, IE, 1" of closed cell to seal the envelope and then combination of traditional insulation.