Well, here's what I figure on dying.
Any Healing keyword powers being done to you brings you to 0 and then some. Of course, most healing uses the recipient's surges as well, except for the Paladin's Lay on Hands, but yadda yadda.
Stabilizing by means of someone else using the heal skill on you just stops your hp where it is, and you no longer have to make saves until you take more damage from something.
If you fail 3 saves while attempting to stabilize, you die. Remember, failing a save is anything from 1-9. If you make your save 10-19, nothing happens. If you roll a 20 (or more with bonuses), you spend a surge and you get to go to 0 hp. The fails don't have to be concurrent by the way, so 3 total fails over multiple rounds mean you're dead.
Also, if you have no more Healing Surges left, you can't do the whole roll above 20 to survive thing, so you better have some help nearby. :lol
If you fall below your negative shock value, you die.
Coup de grace is now just an automatic crit of any attack made on a helpless adjacent opponent.
I like this system by the way.
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Other random pointers: Spook, don't forget to use your character's Second Wind as a minor action thanks to your Dwarven racial. Also, your son could have used Elven Accuracy on one of his Ranger's many misses to turn it into a hit, don't forget about that.
All in all, I like the way things played out, and next combat will be faster. I figure I don't have to memorize all the powers (because that would be impossible as a practical matter anyway), but I could work on being familiar with the powers you've all picked. The main thing I want to review again and again is the Combat rules, and then, to some extent, the Skills rules, and the DMG's content.