Anastasia Beverly Hills - Tinted Brow Gel - Espresso

It's hard to find good tints for redheads.. Should I get the auburn or caramel? :)

What is the best color for people with gray/white hair?

Conflicting info: under the pic, it says, "size: 0.28 oz ..." under the product description, it says, "size: 2.5ml/0.085 fl. oz." what's the size?

How do I know what color to use? Did I read something about using two colors for more natural look?