On Dragon Throne of Tarkir, is “this creature” a fixed pointer to the creature that activated the granted ability? ie. it's locked in on activation.

Or is it floating? ie. it's checked on resolution.

if I activate the ability while the Throne is equipped to creature A and prior to resolution the Throne is somehow moved to creature B, does it determine X based on the power of A or B?

If the Throne isn't attached to any creature on resolution of the ability and creature A is still on the field, does it us A's power for X? or is X considered 0?