well of course none of us would know for sure but i would say that there is almost a 100% chance that scenario 2 of your homicide example would not be counted at a murder since the game would know that the other person initiated combat, games have been able to track stuff like that for years.
as for the duel example that really depends on whether or not there will be a dueling mechanic in game. practically all mmo's have them but it has never been mentioned as far as i know.
as for the stealing example i would imagine that since the item is flagged as stolen then stealing it back is not a crime but the crimes you commit along the way would be. so if you break into someones house and get back your item then you didn't steal but you did trespass.
its also worth noting that if someone says that they will attack you and then seem like their getting ready to attack you and you attack first then your the criminal. I mention this only because i feel like some idiots might actually think that the game will somehow know that the other person verbally instigated the fight. Sometimes i see people talking about game mechanics in COE as if the game will have nearly sentient AI running around.