I would try to carb load leading up to the hike. The day of the hike, only bring stuff that you really like to eat, but a variety of things - you never know what will be appetizing, if anything at all. I try to eat most of my food before leaving Trail Camp. I have a hard time eating above 12k.
As far as clothing goes, there is some info regarding what I plan to carry on my blog. YMMV -
http://www.hikinggeek.com/2014/06/11/mt-whitney-trip-planning-september-6-8-2014/
