Yes, I actually thinlk it adds to the depth, looks nice.

If you can get by with a smaller garage door on the garage addition I would suggest matching the existing wall width of 4'-0". Wouldn't be the end of the world if you don't but I do think it would be more consistent. Good luck!

I would be more concerned with the diminished functioning of only 2 feet clearance. Much tighter squeeze getting in/out of car. Always build for more garage space if possible. Only reason to go smaller would be lot line issues.

I think the walls should be the same, if possible. The rendering seems to show a larger garage door in the addition. I agree with @Norwood Architects' suggestion.

From a practical point of view, it is more convenient to do inside without walls. This will increase the space in the garage and relieve the inconvenience. It all depends on your purpose and desire.