Would these work for a guy as well, they look comfortable and cute, but would they fit?

I'm 6'1", 37" hips. And I wear a size small. They are a bit small in the front and didn't quite hold me in until I washed in hot water. Now much better fit.

are these 100% cotton ?

No they are 95% cotton, 5% spandex

I've got jewels, but I don't like pouch thongs because they let everything sag. If I'm a 30-32" waist, what size would be best?

Ive lost a lot of weight from 230 to about 180 . Im 5.11 and at heavy the xl was a bit loose . Im finding at present im comfortable with med. So i would assume youd be more a small

My hips are 48 inches and my waist is 37 inches what size should I get

My hips are 46 in my waist is 34, and I got an extra large and they don’t dig in at all. They set a little high on the hip, but not bad. So I would assume an extra large should be fine.