Q's: Religion & Cycling

[Eight]

I have had a problem finding answers to any of these questions and I am wondering if someone could either point to where in the manual the answer is (or just provide an answer):

#1 - I cannot figure out how to adopt a state religion. I played through 200 AD and still get the message "You cannot adopt Buddhism/Hinduism/etc."

#2 - Is there a keyboard shortcut to cycle through units? I can click "W" to skip a unit in the order, but I'm wondering if I can just cycle through them.

Thanks.

[Solver]

You must have the religion present in at least one of your cities to adopt that religion as your state.

\ will select your previously selected unit, at least.

[DRoseDARs]

You need to have either discovered a given religion first (before other civs) or have a religion infiltrate you civ from abroad. At least that's my understanding thus far in play.