ASSERTING CONTROL
After revealing an Order Marker on this card and instead of taking a turn with Venom, if you control Venom's Host, take a turn with it. If you do not control Venom's Host, remove all Order Markers from its card, take control of it, and take a turn with it. When Venom is destroyed or removed from the Host's card, return control of that Hero to the player that controlled it at the start of the game.
No to the first question. Losing Control can still pull Venom off the card of a friendly figure with Mental Shield.