If Lord Vorun‘thul disengage from an Enemy, which facing he has?

1. Front to the Enemy

2. Direction of owners choice

Same question for using his skill, if he is not engaged? Which facing?

2.

You're just placing the unit AT range 2. As long as any part of its base is at range 2 of the starting position, it's a legal placement. Facing can be anything.

The important thing here is the word Disengage. It's a game term. If VT uses his skill, he's not disengaging, so ignore all of that rules text.

The Wording is „Not enganged“ Not disengaging