Lomecevak,
I had to wait to answer this point till I went to work and asked an MD80 pilot about their EGPWS (enhanced Ground Proximity Warning sysyem) just to make sure I was right.
If your friend was close enough to the front of the cabin to hear cockpit crew talking (Put the gear down NOW!) he would have certainly heard the EGPWS saying "Bank Angle" in a VERY loud robotic voice every time bank exceded 60 degrees or so. Also, the terrain warning would have activated with high sink rates below 2000 feet. (The enhanced portion would not have the "Whoop Whoop" it would just say "pull up" or "terrain", if you ignored it and got into the old style envelope then you would get the "Whoop whoop" before the message) anytime the path of the aircraft gets within 60 seconds of the ground. Its suprisingly easy to get that portion of the EGPWS. 2000 feet a minute 2000 feet above the ground (not that high a sink rate) can get it in the right circumstances. Also don't forget the "sink rate" and "glideslope" calls that a severely unstable approach is likely to generate, but those are within the last 1000 feet or so (which is 1.3 minutes long btw)...
But basically anytime the sinkrate (in feet per minute) exceded the altitude of the aircraft he would have heard a LOUD computerized voice saying "pullup" or "terrain".
That being said, a likely scenario was the crew was descending far out on the localizer on the autopilot. Either they encountered the wake of the aircraft in front of them or the aircraft infront of them bent the localizer beam causing a rapid roll reversal as the autopilot tried to fly down a beam experiencing intereference from a preceding aircraft. As soon as that happened the crew would have disconnected the autopilot which will cause a loud non verbal alarm to ring in the cockpit. Furthermore if they were running into wake they might have climbed breifly above the glideslope (not really climbing, just slowing down the rate of descent untill they were a few hundred feet above the glidepath but you get the idea) and then slowed down as much as practical (hence "get the gear down now") to increase seperation with the aircraft infront of them.
When an autopilot attempts to track an interferred with localizer beam it can be quite ugly, though not dangerous. The autopilot has bank limitations that will prevent it from going past 35 degrees or so, but it might get there in a hurry, especially in localizer mode...
Cheers
Wino