I kinda let my mare get away with this.
Instead of scolding her for eating on the trails, I taught her how to eat while walking.
We don't have grass on the trails, only tons of tree branches. If there's one in front of her, she grabs it. If she thinks she can reach it while walking by, she'll try it. But if she can't grab it by the time she has walked by it she'll keep walking and look for the next branch coming up. It's kinda funny to watch. Lol But I don't ever have to worry about her stopping. I rarely even hold the reins on trail rides if all we're doing is walking.
But anyway, back to the questions...
If you ride english you could try grazing reins. I don't think that would work out too well for western though. From reading the other posts it sounds like you got it down. Now the trick is keeping up with it.
As for kicking out, I would only worry about it if you think he's in any pain(but from the way you described it he isn't), he's trying to either kick your leg or get you off him, or if he's trying to kick at other horses.
If he's trying to get you off or trying to kick other horses, I would carry a crop and give him a firm(but gentle lol) whack on the butt and say NO! Or QUIT IT YOU BIG BUTTHEAD! Or something like that to get the point across. Haha