The varitions don't change much. Ability, opportunity, jeopardy (wow, someone else recognized the necessity of those points!) are present. Original scenario, or modifications A or B, he's still armed, violent and coming for you.
Again, consider the likely angles involved. He's likely to shoot straight-on thru the door; are you going to be there? I'll be way the heck off to the side. He shoots blindly; are you going to stand there returning fire or will you get the %$#@ out of the way (or both, not always practical)? Why be right in front of the door when you can get to cover?
Again, Rule #4 DOES APPLY: KNOW YOUR TARGET. Being a hermit, I know that anyone on the other side of that door at oh-dark-hundred is a threat; those of you with kids CANNOT make that assumption. He may be shooting thru the door; is he holding little Bobby in front of him while doing it?