The secret about color neg films is that when you have them printed at a lab, the machines automatically balance the color depending on which film it is. Seeing a difference in color when lab-printed is totally up to chance, because besides the emulsion settings most places leave auto-correct on, or their tech adjusts them to fit what he think looks best. You may get better results scanning the film yourself.
As for exposures, I did some slot canyons earlier this year, and it varied from f/2.8 and 1/50 to f/2.8 and 1/4 or 1/2. It depends on the time of day and where the sun is. I've got all the pertinent data on the photos in my slot canyon
gallery, but unfortunately I shot digital in there
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K10D, ZX-L; DA 14 f/2.8, DA 18-55, DA 50-200, FA 20-35 f/4, FA 50 f/1.4, K 200 f/2.5; Sigma 28-80 f/3.5-5.6, Quantaray (Sigma) 100-300 f/4.5-6.7
Diamond Bar X Photography