OS X El Capitan 10.11.6. MacBook Pro (Retina, 13-inch, Early 2015).
I wouldn't worry about any memory issue until there's pressure or a problem.
The system is designed to use all the memory it can since memory access is faster than network or storage access. Self-managed systems can reduce the allocations once you have other needs. What your snapshot shows is nothing else needs RAM, so the system is using it all for other tasks.
You could dig into Finder's allocations or try removing Dropbox to see if there are leaks. Even if Finder is leaking, it's not causing any harm (perhaps yet). You can also log out and log back in. If you watch the EMA usage each hour for several hours, you can quickly determine if Finder indeed is leaking memory or if you just have a usage pattern where it allocates a lot of RAM.
I see two explanations for the usage:
Either you have loaded something into Finder that takes up a lot of memory (I have no idea what that should be), or you have triggered a bug in Finder so that it leaks memory.
If you believe the memory usage is due to an error, you can always just quit Finder so that it restarts - the memory usage should go down immediately.
No there is not.
Definitely check in your Finder > Preferences > New Finder windows show: (select something other than 'All My Files') even if you have already done this in the past, as it resets itself on its own behalf, because it's really poor software.
It's nothing malicious, though, just poor software. Try GNU/Linux.