Apple TV2 - How to clear space?

Recently started having problems with my XBMC v.11 install on my Apple TV 2. The MovieDB add-on stopped working and my background images will often fail to load.

Not sure of the cause of this problem, but perhaps it is related to the lack of space on my internal flash drive? Just checked it, and it's at 100%

I read through the FAQ's, and found this entry:

4.10 Not enough space/memory
Shortcut: #Disk_space
Have you run out of space on your ATV2? Check with (via SSH) the df -k command. If any /dev/disk* filesystems are at 100%, use du -h / to see what's taking up space. or to show which files are, for example, bigger then 9 Mb do find / -size +9000b
First places to check are:
/private/var/mobile/Library/Preferences/XBMC/addons/packages
/private/var/mobile/Library/Caches/AppleTV/Video/LocalAndRental
/private/var/mobile/Library/Caches/AppleTV/Video/Other
/private/var/cache/apt/archives/
See also #Thumbnails for saving space with smaller thumbs or moving them to a network location.

I can find these files.

My question:
1) Which files can I delete? Can they all be erased without undue harm? If not, how can I determine the appropriate files to remove?
2) While I still want to clear space, will that help the issues I noted above?

Thanks!

J