However, there is another option. You've got yourself a couple of pretty rubbish screens there. Maybe you could consider replacing one of them with a better screen, and going for the cheaper calibrator?
Honestly, no. They really are neck-and-neck. I find the X-Rite perhaps a little easier to use, but the Spyder slightly more feature-rich. You'd be happy with either one, so go with the one that you can find for the best price.
If it didn't have the beads all over it, it would be a fairly simple matter of Channel Mixer or even Hue/Saturation.
But the beads will make it a heck of a lot more difficult.
I think you should find a forest photo that you can put behind your subjects. That's the only way you'll make this work.
https://www.facebook.com/graystarphotography/photos/a.427923724420188/853741078505115/
Open it with liquify, which will stretch the iris all weirdly. But that's ok. Once you've liquified the eyelid to where you like it, you'll copy the other iris across and mask it in.
It's impossible to tell on the basis of just one photo.
Don't worry about it for now. If I see a pattern of darkness in your raw class posts, I'll let you know.
No, that's right. That's exactly how it's supposed to work. You can make any modifications you want, and simply save and close that PSB file, and it will update in your PSD file.
Always use cloning if you can.
But if you feel it's not an option here, you can try this Channel Mixer layer:
R +100, 0, 0, 0
G +79, 0, 0, -9
B +61, 0, 0, -12
(Make sure you enter those numbers in exactly the correct order.)