I won't address the issue of the HUD here. Others in the forums would be of greater help along those lines.
As for offing your player, you need to set up a timer. I like using dynamic lights for attaching scripts. Set a light into your map. Make sure it is set as dynamic. Change its color to ffffff. This is black (invisible) light.
Name the script below something like killplayer.fpi and set the script as the Main in the light entity. Note that you'll have to set the path to your intended explosion sound following the plrsound= command. Also note that I used the plrsound= command instead of sound= because the sound will seem closer to the player rather than to the entity to which it is attached. Hope this helps.
;Artificial Intelligence Script
;Header
desc = kill player after delay
;Triggers
;get our timer started
:state=0:etimerstart,state=1
;check our timer-if time is up play the big bang.
:state=1,etimergreater=360000:etimerstart,plrsound=path to your big bang sound
;give a delay sufficient for the sound to play fully then off our player - subtracting 1000 from the player health should be like exposing Superman to kryptonite
:state=2,etimergreater=1000:plrsubhealth=1000,suspend
;End of Script
Life is about living.
