Is this how making an asset works?

I'm still trying to figure out how NFT's work, especially since RVN seems to be leading the charge with NFT's.

Say I create X amount of pieces of art that is a limited edition. I would have to either mine or purchase 500 RVN to "burn" and then I get to create my own token on the Raven blockchain. I can name it whatever I want and decide if I will be able to create more tokens or if its set in stone. Then whoever wants a piece of art gets the token. Here's where I get a little confused:

– Does the art or whatever (I've heard of deeds, stock certificates, etc) being used with NFT's have to be digital? Or could it be a physical object as well, say an autograph from someone famous?

– Does the holder of the NFT ever get the asset? Such as the painting, certificate, autograph, etc.

– What prevents someone from creating 5 pieces of whatever, but making 10 tokens and essentially selling the same thing twice? Obviously it would be on the blockchain, but if you didn't look to see what was going on, could you get scammed easily?

– Will the burner fee of 500 RVN also be halved when the coin does that next year?