I'm unsure about the gun runners key, But I am sure its impossible to be non hostile to the fiends outside of vault 3. The man that shoots himself is Chief Hanlon (spellcheck?) you can read more about that quest and how to prevent his suicide here: http://fallout.wikia.com/wiki/Return_to_Sender
from that link
Return to Sender: the player finds out that Hanlon is falsifying field reports. Once discovered the player can either let Hanlon continue with his plan, turn him in to the NCR authorities, or convince that falsifying the reports is pointless and Caesar is dead (Only available if you actually killed Caesar).
I don't want Hanlon to continue his falsifying reports, and I don't want to do the Caesar thing becuase I am trying a 0 kills game...
so I want to turn him in to the NCR authorites...but I don't want him to commit suicide and the only way I can do that is to find the key...
that Wait trick is a bug so that is cheating. So any ideas where the key is?
I know asking the forum is cheating too but I have left that mission(and the gun runners one) alone for a couple of months...so I just need to know where this key is and get these missions over with.