Oh! and please don't forget TA Only BEFORE you descend otherwise a TCAS RA to reduce V/S could be triggered. That too is a little hidden gem and often not complied with
Oh my god!
So much better to hit another aircraft than reducing your rate of descent.
Review the your aircraft oxygen time ....on the 737 its either 12 or 22 mins,on the 12 min uou can descend from 41000 to 17000 ft then level off for 5-6 minutes then to 10000 ft.
Beware of MSA higher than 10000 and temp correction...
Cncerning your emergency descent,
Whatever the scenario it becomes necessary to make an emergency descent. Do you:
1. Mayday ATC and inform them you need an E.D. and wait for a clearance?
2. Hurtle on down and THEN inform ATC what you are doing?
How many pilots in your aircraft?if more than one then one asks for descent while the other flies...you will get an answer very quickly,if not,broadcast on 121.5 and think of an offset if you are on an airway.
For the rate of descent,you use speedbrake and mmo/vmo (unless structural damage/then 280 kts and possibly gear down),for the level off just as your QRH says......