I get the galloping/not (only once per phase).
Let's say -- non-hypothetically -- that the White Knight has hired O3 and then attacked the Patrol, who are conveniently there.
1) The Order and Patrol have no special relationship, so that's OK. No treachery, right?
2) I think I grok Denizen assignment, no problem. O2 lures P2 and WK takes the others.
By grok, I think you're right.
3) But O3 and P2 each have horse. The horses seem slower (I guess they are bigger targets) than the main people. But each basically works like a manuever against the others attack? The attack is in the O3/P2 box, and the defense is the O3-H, P2-H box? So you have to undercut the horse or line up on the horse?
Hmmm, I don't recall if you're supposed to try to hit the horse, or the individual riding the horse (assuming we're not using Advanced Combat Rules). I believe you would be trying to hit the horse in the case. So then yeah, you have to undercut or line up with the horse, taking into account the horse's vulnerability and armor. Once the horse is dead, then there's only the native to worry about.
In Advanced Combat, it's possible to kill the rider without killing the horse (though the horse just dies anyway).
The native on the horse, that is considered to be the attack. The horse is considered to be the maneuver.