"A British helicopter flew over the bridge and the pirates gave themselves up immediately"
It's pretty obvious that they did it because they realised the secure bridge area meant they couldn't get control of the vessel. Securing vessels in this way seems such an obvious precaution, I imagine it's relatively inexpensive, and is something that can be retro-fitted into existing vessels.
No, but Pirates tend to fight shy of anything bristling with guns and a well trained crew. This of course be treated as an act of war, the pirates would certainly get nothing in terms of financial remuneration and would almost certainly end up dead.
That assumes that they could actually take over a warship, which I doubt.