maybe your wind is too strong.

ctrl S to save. simple. like in any program.

Make sure your clothing patterns in Marvelous Designer are not overlapped or the UV maps in Substance Painter will be overlapped as well.

Pockets in Marvelous Designer are basically square patterns which are sewn on to square internal shapes with the top internal line not sewn on.

Any 3D shoes will work with Marvelous Designer, ther are no specific "Marvelous Designer shoes".

To add 3D buttons you'll need to export your clothes from Marvelous Designer and then create them in ZBrush or other 3D program and add them there. I...