I like Omatako's plan of action. I would add that as skipper, you should assign duties, so many of the above tasks can be carried out simultaneously, saving precious time. I'm no longer surprised during situations (sailing and otherwise) that several people stand around doing the same thing, or all watching and give advice to the one person acting!
This question really reinforces the importance of situational awareness. When flying, if not actively engaged in another task, I'm constantly looking for where I could land if an engine were to fail, and always maintaining an awareness of my position, so if need be, I could give an immediate, accurate position. Its become so routine, its not a worrisome or energy consuming task. Its almost my way of relaxing.
On most of the boats I've sailed offshore aboard we discuss emergency management plans. Everyone is assigned duties to perform depending on the crisis. And if it's a race boat w/ lots of crew we try to always have a backup person.
For example: On a delivery if there is water in the boat everyone OFF WATCH is responsible for searching their sleeping area. Check the through-hulls/seacocks, watertanks, etc.And then move on to area's that haven't been searched yet.
IF an abandonship situation arises, there are duties assigned for grabbing the ditch bag, making Mayday calls on VHF/SSB/Sat phone, who is going to deploy the raft, etc. AND since there may be injuries.... backups to those duties.
I would disagree w/ DAVIDPM re: the PanPan to the CG. They are not going to come out just yet esp. if you let them know you are keeping up w/ or have found the source of the leak. They WILL appreciate knowing exactly where you are AND that if your Epirb goes off it is a legit emergency. That will save the time it takes them to call your contact person and verify that the boat is indeed offshore. Gets YOU rescued sooner and keeps them from a wild goose chase.