If your crashing just by caching thumbs then that would indicate a problem somewhere as that is not normal or expected behavior. I agree with pkscout that the texture cache maintenance utility is good, but I think most casual users could find just deleting the Thumbnails folder an easier task. It usually only becomes an issue when you have changed around your sources leaving stale artwork in the cache, or with some plug-ins that cache online content. There is a add-on in Kodi’s repository called “video database cleaner” that can take care of the latter without having to go to the terminal.
As for relocating the folder I think I cover it pretty well in my howto…