Why is Finder listed as using more RAM (24 gb) than is on my machine? Bug?
You're showing that you do have 16Gb installed - that's the Physical Memory number shown at the bottom.

That 24Gb number is for compressed memory. Because it's compressed, and might not be being physically used, you can go over the physical limit.

This explains it: http://appleinsider.com/articles/13/06/12/compressed-memory-in-os-x-109-mavericks-aims-to-free-ram-extend-battery-life 

24Gb RAM used for Finder is still a little excessive though.

If you look, you're using 12Gb of swap, which is where your extra memory that's being used is coming from. You're swapping it all out to disk.