White Balance for Antelope Canyon

Hi,
I've had a DSLR for the last 7 years (currently have D7000) but have only really recently started shooting in RAW full time. I'm spending more time in PP on my images and I've reached the stage where White Balance is starting to become more problematic.

I've looked at a number of solutions and think I will get myself an expodisk to help take accurate WB measurements.

However I have a few questions about it's use and white balance measurements in general.

1. I am going to Antelope Canyon next year and only given the relatively short shooting time I will get in the slot canyon itsel want to go in fully prepared. Am I correct in thinking though that if I take a custom WB reading in the canyon that it will remove all the warmth from the reflected light in order to push the grey back to neutral grey? How then should I set WB in the canyon to keep the colours true to what the eye sees.

2. Leading on from this, how do you set WB manually when taking sunrise or sunset shots? Surely there is the same issue? If you set WB manually surely you have beautiful colours being removed from the light so your grey card/expodisk is rendered a "neutral" grey.

Sure these are pretty simple questions so appreciate any help!

Adam