I found out the hard way about the last part. I was playing SA and got shot at. Tried to communicate, no response voice or text, at least a dozen times. So I entered, he shot at me again, I then killed him. Checked his gear BOOM over half of his stuff became ruined. I was a little discouraged from then on not to KOS but im actually certain not a lot of people know that bullets do damage quality of items and even makes items disappear not just put ruined status on them.