Some very good advice from Dublinpilot the only thing I would add would be to item 10.
Getting out a MAYDAY is vital but it will also need a location, the best wat to do this is to put your GPS on the page that gives the radial and distance from the nearest VOR. As you are going down you must broardcast this position in 121.5 untill you are about to hit the water.
Since 9/11 airliners are all listening on 121.5 so you will have people who can relay your position even if your last transmition was done at thirty feet.
The reason to use a VOR R/D is that this will be known to most of the airline crews listening and they can relay this position without any chance of error.
This should get the rescue helicopter near enough to your position that PLB you have can be homed on using VHF or UHF.