The scenes that I have read so far are somewhat freaky.

What Tylin did to Mat was no worse than what Alanna did to Rand.

Though Mat's situation I think is less permanent (if that is the right term) than Rand's.

A warder bond lasts until either dies or until the non-warder is severed; unless the non-warder releases (or passes) the bond.

Granted he could learn if he was so inclined which as a whitecloak I highly doubt he would be, but as of the end of KOD he can not channel.

I am not sure if Galad could even learn.

Elayne might have gotten channeling through just Morgase, Rand through just his father, and Moiraine from just the non-Damodred side of her family; though I am not certain on any of these.

"Galad was not distracted. Every creak of saddle leather was clear and distinct, every ringing stamp of hoof on paving stone. He could hear the flies buzzing ten feet away as though they were at his ear. He almost thought he could see the movements of their wings. He was one with the flies, with the courtyard, with the two men. They were all part of him, and he could not be distracted by himself"

This does not prove that Galad could channel or even learn.  Awareness of surroundings I think is part of the void.