I can only comment on the cd-equiped type-r gt model (07 facelift at that) but there is standard support for wma and mp3 on cdr.
I've put 99 mp3 tracks on a cdr and it works fine (reason for 99 is that the display on mine supports two digits for track number)
Perhaps someone with satnav could confirm whether there is dvd-r support (I seem to remember the sat nav version uses DVD's - hence the lack of 3rd party speed camera database support you'd expect on HDD flash memory style GPS systems.....)
If you have the 8CD changer, that's 800-ish tracks
