Photo - resize to proper home demensions

[Allen42ACJ]

Hi Joel
Yes on the 16" OC.I was thinking the length of 2x lumber coming in 2' increments.
8' 10' 12' 14' and so on.
If your going with I-JOIST more flexibility because the extra is figured for another place.
As a framer I like 2x6 walls because you can get longer plate stock,
Keeps the walls straighter with less joints in the top plate.

Your garage should be 24' wide for 9' wide doors.