1. You are correct. Training is global and there is no range limit on the howl's training.
2. First, lets define and distinguish "Engaged," "Engaging," and "Becoming Engaged."
Engaged is defined as being in B2B with an enemy model.
Engaging is when you model moves into B2B with an enemy model, regardless of whether that movement is forced. Eg, when you use you manouver to move into base with an enemy, or when a longhorn uses the move part of Clear a Path to base an enemy model.
"Becoming Engaged" happens when an enemy moves into your model. You model did not moce, but it became engaged.
Now Disengaging. This happens when a model leaves base contact with an enemy. Forced movement ignores the move penalty, but is still disengaging. After breaking contact, the disengaging model cannot engage an enemy model with the same move.
The Howl's training triggers when an enemy model disengages one of your models. You choose one model, and it may make one 4" move toward the disengaging model.
Knockback triggers a disengage. The Howl and bloodmasks can only Knockback one enemy each. So suppose you have a Howl and 6 bloodmasks in a combined activation. If all 7 are B2B engaged and all use Knockback, you have up to 7 Training moves. One for each disengage.
Elsis could potentially cause 3 disengages if 3 enemies are B2B with her and she assigns a die to each. Longhorns Clear a Path causes X disengages, depending how many enemies are B2B with it when the ability is used.
However, Kor Kallum's toggle only affects enemies that begin activation engaged with him, or become engaged by him. So he'd have to move into base contact.
Take the combined activation above. Assume Kor already activated his toggle and begins unengaged. Move 1 lets him move 4" towards the disengaging model. If this brings him into base contact, the knockbacked model would take the toggle attack. Disengage 1 is resolved. Assume you pick him for move 2. He is engaged, so must pay the disengage cost (it's not forced movement) and cannot reengage. So Kor gives up 3", and can move 1" toward disenaging model 2, but cannot engage any model. Now move 3. Kor is unengaged again, so can move 4" towards model 3, and engage models. Engaged models take toggle attacks. Move 4 is an unengage. 5 reengages. 6 unengages. 7 reengages.
Given Kor's 80mm base, plus the "toward" move resitrictions, it's hard to imagine you'll easily contact tons of enemies this way.