I know what some of them are, but could someone explain to me what the rest are?

Mk2a:20G (Player model and size of drive I have)
+38C/+100F (Internal temperature of the unit)
Playlist: 23c0 (No idea)
Fid: <blank> (No idea)
Cac:593 (No idea)
Buf:81 (buffer of some kind, but what?)
Fre:121 (Free memory or something?)
LoadAvg:0.18 0.14 0.07 (CPU Load, not sure what numbers are which though)

Thanks for any info anyone might have.

-Allistah