Forests and Leaders

[BigDuke66]

Doesn't matter if the leader is wounded or killed, he is removed from the game. And indeed it doesn't matter if he was mounted or not.
Usually a replacement leader should appear but it can be that there are already multiple leaders for the brigade, in that case I think one of them is in command now. The next turn just mark one units of the brigade and turn on the organization highlight function and you should see all units of the brigade being highlighted, if turning on the leader on top function you should be able to find the leader for the brigade now.

Regarding movement in forest besides elevation, in case a unit was disrupted it got less movement point and won't be able to make it as far as the others.