Fall of London Card rules questions

Palamedes wrote:

Hi,
I have some doubts about the card rules from Fall of London:

The Guardian
When The Guardian is locked to enter combat by special text, who is considered an acting minion (who plays first)?

Name: The Guardian
[FoL:2]
Cardtype: Vampire
Clan: Nosferatu
Group: 6
Capacity: 4
Discipline: ani cel pot
Camarilla: The Guardian cannot perform directed actions unless you control a ready unique older Nosferatu. The Guardian can lock after resolution of a successful bleed against you to enter combat with the acting minion.

Cardtext.

Palamedes wrote:

The Shard, London
The card says "card you play", not "you and your minions". Since the cost can also be paid in blood, I assume the card interacts with minion's cards as well (not just Master cards)?

Correct. Minion cards are played both by the Methuselah and the minion.

Palamedes wrote:

Mobile HQ, Operation Antigen
Is locking Mobile HQ to enter combat cost of the successful action, or is it locked when the action is announced?

Name: Mobile HQ, Operation Antigen
[FoL:1]
Cardtype: Master
Cost: 2 pool
Unique location. Operation Antigen.
An Operation Antigen ally you control can lock this location to attempt to enter combat with a vampire as a +1 stealth action. You can lock this location to add enough life to an Operation Antigen ally you control to reach their starting life. You can lock this location and burn 2 pool to cancel an action card that targets an Operation Antigen card you control as it is played; its cost is not paid.

Lock the card in order to announce the action.

Palamedes wrote:

Enhanced Coagulant
The strike works only against vampires? You can't deal 3 damage to an ally, right?

Correct, there must be an "opposing vampire" in order to use the strike.

Name: Enhanced Coagulant
[FoL:2]
Cardtype: Equipment
Cost: 1 pool
Weapon.
Strike: 3 unpreventable damage and put this card on the opposing vampire; it becomes a card with "Cards requiring a Discipline cost this vampire +1 blood. After this vampire successfully hunts, burn this card".