Well that are the person-involved risks
1) yes you can - dunno whats the point of being guarded anyway (NCR) you can easily kill within city
2) yes, got it, I dont stand in group of people - avoiding risk
3) outdoorsman skill - related individual problem its good
4) no not doing nothing, and no I dont mean trading with other people because you can step aside somewhere or even on the worldmap, my point is you cant evade stealing while bartering in NCR - SO ANNOYING ( dont tell me to move )
1) You don't understand, one guy SMGing you, you both die, other (friend of guy who bursted you) picking up your items.
1a) I killed (EDIT: oh noes, I didn't kill him, guards crit me instantly, so I insta-killed him only to 0 HP) innocent at NCR only once (don't include bombing), but that moron didn't want to answer on my messages, that I want to buy all ammo he have, he didn't even said "Get off" or something, just ignored.
2) You don't need to stay in gruop, you trading with NPC, another bluesuiter comes near, don't doing any actions behind you, so you don't expect him as a thief, and he's not a thief really, he simply going close to Sha Enin and then setting dynamite on 1 second and then Boom, Sha Enin and everyone who was standing near him are dead.
3) No, I don't talk about YOU encounter THEM. I talking about THEY found YOU. Your outdoorsman won't help you.
4) The same as 2th, while you bartering at NCR, everything can happend, you can barter not only at NCR... there're alot towns at California and even more NPC traders than towns.