Want to change the garage access from one side of the wall to the other
Putting in a wall with door on the south end is pretty basic. Just take down the door (leaving the existing wall structure as is) and all the trim around the opening. Then build the stud wall in the opening. You'll need to re-side or this wall will look bad.
The west wall is a challenge. You have to support the ceiling and attic as you rip out the west wall. The door opening requires a large built-up beam across the top of the opening. I would track down a good remodeling contractor. This part of the job should be done all at one time. You'll probably need permits for such a major structural modification.