Generally speaking there's two main styles of construction.
First the older style known as "stick & bat" where the walls and ceiling as made of 2" x 2" studs with the interior paneling and exterior skin act together as a good part of the structural integrity.
Then there's the newer composite wall panel system developed for the trucking industry. Usually using the FRP (fiberglas reinforced panels) method of construction. This allows for very rigid, well-insulated, light-weight walls.
IMHO, you'd be far better off trying to find a floor plan that works for you then just make minor changes and upgrades as you wish.
