1. Goto the very center of mid. Look left or right, you'll see underground passages. It looks like a dead end. But you'll notice one of the walls has a slight crack in it.
Shoot, forever, begin.
2. Stronger is pretty much done. The only outstanding issue that I'm aware of is the fact that in match mode, the "doors" don't come back down unless the map is restarted. But on a pub, it works just fine. I haven't put up a final bulid yet though. Soon as V3 gets off his ass, and gets the map pack going, I might actually finish it.