Can't access themes? Sounds like you need a reflash, and I think #2 and #3 may be related.

#4 is caused by tracker-indexer coming with a stupid configuration. You need to customize ~/.config/tracker/tracker.cfg. Basically I set it to only index folders where I keep my media files, and some default folders. If you tell me where you keep your music, videos and photos I can help you come up with a better configuration.

Can't help you with #5, but Ctrl-Backspace is the usual way out.