Money

Does it work as a collection or should I use a single photo? If the latter: Which one should I choose?

I definitely think this works as a collection.

You might consider restructuring the photos to a squarish configuration (two on top of two) instead of the rectangular presentation. That is a thought that came to mind, but it's definitely not a criticism; I think this is a fun piece. I'm not sure of the message you are trying to convey, however.

The 3rd photo from the left is the most unusual because of her eye color and whatever that is on her tongue...it's different than the others by quite a bit. It seems to me that that would be the one to either edit or accentuate, depending on your goals.

Amy