1 - Rose says she can teleport an AC/AB 'one Space away'. I believe this means to put the monster 1 space away from Rose (not move it 1 space from where it is), correct?
No, move the monster 1 space from where it is (it's mind controlled.)
2 - There is a Dark Past card that says the Hero must take 3 damage or 3 corruption. But to trigger the Dark Past you have to end your turn with max corruption...which then would convert the extra corruption to damage. So...3 damage or 3 damage...huh?
There is one or two cases where you reveal your dark card without maxing your corruption. Can't remember them off the top of my head.
3 - Another Dark Past says the Hero becomes a 5/5 monster for the Sin side. Does that player switch sides? Or is he effectively dead and select another character.
Player selects another character. Sin controls that character as if it were a 5/5 monster.
4 - Can a single Hero get the bonus from two identical Upgrades? Dual mini-guns?
I think so.
5 - Players can save any number of Extra Action tokens from round to round?
Yes for Heroes.
No for Sin (he loses extras at end of round.)
6 - If a player(s) gain more than 1 Upgrade at once, should you replenish the pool back to 5 after each one or just take multiple from the 5 shown?
It's not clear, play it how you want for now.
7 - The Darkness Within 3A allows you to sanctify Districts. Once you are past that part of the flow chart do you think you can still Sanctify locations?
It's not clear but i'd say no.