Good advice on the first part, but as for the second WRONGO! Tennessee has what is often referred to as a the "reasonable person" standard. If a guy is pointing anything that realistically resembles a weapon at someone or you it would be justifiable defense of a 3rd party.
Same as a furtive movement shooting. "I told him to take his hands out of his pockets and he went like he was going for a gun."
I'll also refer to the DeAuntae Farrow case. Kid has a toy gun, looks real, points it at officer and refuses to drop it. Kid catches a round. The cop was ruled justified, but he left his job over it because of idiots like Jesse Jackson, etc. Even though that case was in AR it still holds true.
I knew that officer involved in that too. I met him quite awhile after it had happened through a mutual friend. Horrible thing to have to deal with, but if the NAACP and trash hadn't made it into something it wasn't he'd still be doing his job. Sorry kind of a side rant there.