No, it isn't padded. It just pushes the butt up.
I would hand wash it and air dry it... just to keep the tightness
I would say 5x.
My waist is 46 inches and I went with th 6x. Mine is tighter at the lower end trying to fasten than at the top. I think you should go with the 5x. I really don’t think you will be able to fasten the 2x. If it’s too big for you they will exchange it for a smaller one.