Well, if you watch the movie, you will see where they show the actual conflict, and they slow down the tape so that you can see that the black guy has a gun.
http://www.salon.com/ent/col/srag/20...gimme_shelter/ has some fairly unbiased info on the events there, like the following:
"When disaster strikes and strikes again -- first with the Angels' leaded pool cues, later with the flaunting of a gun and the slice of that knife -- "
I do not know about the two people killed in their sleep, but there was no association between those deaths (if they in fact happened) and the HA.
If you watch the movie, you will see the one time where bringing a gun to a knife fight did not exactly work out the way one might think it would.
As far as how nice the HA are, I have met and partied with more than I can count, and never had a problem. However, I have seen them clear a room very quickly when one poor soul accidently bumped into one while dancing.
They tried being nice guys in the 1980s, and then some asshole from a chump club decided that he was tough and killed an Angel, so no more Mr Nice Guy when they were in large gatherings where reputations were involved.
I stand by my earlier comments though, they are great to have on your side, but they make rotten enemies.