It's the "warmth" of your White 9300 is recommended for Web output, while 6300 is the white point close of the one of paper, so if you're outputting to paper, choose 6500
D50 is I think a setting for the light boxes that the photographers use.
Take my answer with a pinch of salt, it's only out of memory...
Check :
http://www.computer-darkroom.com/col...olorsync_1.htm (don't let the numbers under the page fool you, use the arrows to go further)
And check all his tutorials, he is a very knowledgeable and helpful person!