How do you know which vane is the cock vane if all three vanes are the same color?

Doesn't matter a whole lot...Each vane is spaced out over a third of the arrow......just look at them, you can see which one it is. It's not diffcult.

Since arrow nocks are no longer glued on any vane can be the cock vane. Just rotate the arrow nock so that you have a vane at 0 degrees (cock vane up) or a vane at 270 degrees(cock vane left) etc.

depending on the rest you have... in a biscuit make sure one vane is pointed up... if its a drop away make sure its either left on a right handed bow or right on a left handed bow...

I would shoot cock vane straight up on a drop away as well.

ya, i guess with a DA rest it really doesn't matter much... old habit from years ago...

To avoid cable clearance issues, I keep the cock vane pointing to the left. I use a drop away. I use all white vanes, and to aid in determining the cock vane during practice, there is a little index bump on the nock that tells you which way the arrow goes on the string. I feel for the bump on the nock and it points to the left as well. A visual check is good too. If I'm hunting and wearing gloves, I have to just look to be sure the arrow is positioned correctly.

Depends on what rest you are using. If it is a Y type, its the vane lined up with your knock. If its a shelf type, its the vane perpendicular to the knock.