The socialCache one is optional, but yes those are the ones. Many of us clear the caches before we startup (or after we quit, same thing) every time. I would never play with stale caches in place. Others not quite so often but as a matter of routine maintenance. The caches exist to speed up the game's access to data so it's good they are structured that way, but they far too easily fill up with outdated junk. Even if they are only 1kb in size each, that means they are pointers to elsewhere where the real caches are which depends on the type of world being played, but they still need to be cleared occasionally.
Other kinds of cache files like the WorldCaches and Thumbnails don't need to be cleared out routinely unless the player is troubleshooting something in particular as those will slow the game down considerably while they rebuild themselves.
