Fabric-wise it covers everything as it doesn't have high cut sides or anything. You could always get a pattern vs a solid to make the suit a little more concealing.
It depends on how big your bum is. Mines quite big but I ordered the right size where it covers buts it’s the right amount of cheeky.
I don’t know what you mean by small girls. But if you mean skinny, I’d get a small
No, it won’t, I wore it for several times when going to the seaside.
Not at all, I’m also small but it fits me well.
Will not see through at all. It is thick.
No, it is sold by one set, if you don’t like the bottom, you can only wear the top.
I'm sure that depends upon your body shape. It did not cover mine
Yes, it can tie to fits your chest.
I think it can’t, seldom sell them separately.