some questions about the unarmed dudes:
-Is each unarmed dude in the line activated EVERY time another dude fires a bullet or just once in the Obstacles Abilities Phase?
Just once. If any number of obstacles shoot, Unarmed Dude shoots a single bullet.
-Does one dude firing a bullet trigger all unarmed dudes in the line or just one?
Yes, it triggers all the unarmed dudes in the line.
- Do several unarmed dudes trigger themselves?
No, but it doesn't make a difference because they'd all shoot if any other obstacle shot this turn.