We plan to visit April 9, 2020. Does the $15 fee include both the upper and lower level of the caves? Can we go in unguided or do the tours need to be guided?

You are Guided through the cave and they take you way way down there it's very in-your-face stuff

There are two separate tours one is the upper tour and the other is the bottom tour The 15 dollar fee is for one tour

Its a guided tour, and worth every penny. You go through multiple levels. I believe they do offer other opportunities when scheduled ahead.

It's a $15 fee for each cave