These are great questions for someone more knowledgable, but as I understand it, If you follow a single point on the surface all the way around the loop, it will spend as much time in high confinement as it does in low confinement.

That explains why folding is important, as for the mobius, I oversimplified a bit. The Wendelstein has 5 folds, making it a mobius, but I think I read about one in Spain that had only 4 folds. That would mean the mobius isn't imperitive, but I'm sure there is a good reason for it.

Really a stellerator doesn't need 'folding' at all, they can be as simple as a twisted torroid. I didn't want to go into excruciating detail though, the more in detail I go the more likely I am to say something that is wrong lol.

Edit: I looked it up, the one in spain is called "TJ-II"