I'm afraid I can't help with the shuffle question.

Now, if you'd like to send me all 6000 songs, I could do some research...  ;)

To change between Celsius and Fahrenheit go to  Settings -> Appearance -> International  and select your location under "Region".

Not at all obvious, is it? I think this one sets the correct time zone as well.

I added my NAS SMB folder by adding a location like this: "smb://192.168.2.21/music". This lets me browse all my music in the alphabetical subdirectories.
Something similar should probably work for you, but you may want to create a public shared folder on your PC if you can't get it to work directly.
Obviously, you should also change the IP address to match your PC. I tried to use the name "NAS", which is how every other device sees it,
but I couldn't get that to work, so I just used the IP address.

I've got mine running XBMC (OpenELEC version http://openelec.tv/news) and it's great!
It plays videos and FLAC files from my network, and works fine with the Lenovo HTPC Keyboard Remote (wireless trackball and keyboard).
I also got this laser cut case: http://builttospecstore.storenvy.com/products/404262-raspberry-pi-enclosure-kit, which gives it a finished look.

For my basic HTPC needs, it's perfect - tiny, dead silent, and it runs from a cellphone charger.