Check out this video tutorial : https://lesterbanks.com/2016/11/marvelous-designer-uvs-maya/ Not a direct answer to your questions, but it will give you a good understanding of the general topic. Also a pretty useful technique in some circumstances.
I am making cloth in marvelous designer, after that i am exporting it: Here I am already uncertain, should i export it with thicknes or without? Are there some disadvantages for the animation when i use thickness? When i dont use thickness i get something like this: at the neck there is a "hole" because of the normals…