1. He has a duty to retreat in NE. .
I don't know NE law but it may have a modifier on it- eg, "retreat if it is safe to do so". An example would be if a thug accosts you unarmed and asks for all your money with nothing more than a few words and a dirty look. You try to walk away from the thug. He then produces a gun/knife. Now it's 100 times easier to argue that it is no longer safe to retreat at that point.
2. ALL the facts that lead up to a shooting are fair game. If you don't believe that ask any criminal attorney on this board. It's all material to the case.
Yes, and as I mentioned before, whether or not the defender runs their mouth plays heavily into this. The less stupid things one says, the less the prosecutor can use them against him to cast the defender in bad light. When a guy comes out and says "Yeah I saw the door open and because I was robbed before I figured it was a thief so I drew my gun, I searched the house, found him stealing my pipes and held him at gunpoint, then called police. Then he made a furtive movement towards me like he was going to hit me, so I shot him" = you just threw all your legal initiative rolls right out the window, rather than having it appear a lot better in court. (Anyone with a working knowledge of english could reformat that statement to make it PC friendly self defense inclinated instead of the prosecution getting away with painting you as "John Rambo, property owner vigilante!" etc.
Once you run your mouth and tell your (adrenaline driven, probably half true due to panic) story to the cops, you can't re-tell or correct it later in court, unless by some miracle the police forgot something procedurally which would make your earlier testimony inadmissible. (very unlikely). Well, you can re tell it, in truth, but not
without a cost... if your statements aren't consistent, this means you will lose serious
points with the jury because they will think you are a flake or that all of your testimony
is untrustworthy, which means it might be, on a good day, ignored.
Saying nothing without counsel present effectively keeps all your cards close to you.... and even if you have a shi**y hand legally, you could still win, but you will make your odds considerably worse if you show the other side you are starting from a weak position.
-Mike