[Zeke]

Also a walk in closet is less efficient than a reach in. I'm not sure how I would achieve that in the design, but the lack of door to the bathroom would have to be changed for me. That upsets the laundry and so it goes. So I give that plan a 5 out of 10.

However, your thought on the plumbing makes a lot of sense which casts doubt on the design as a whole.

Sorry, I can't help on the minimum size. But there is a lot of information in the IRC. Min bedroom and bath sizes, fenestration and egress requirements that tend to add up.