Axis & Allies Developer and Playtester; War of the Ring Editor and Playtester
When a card states that a person needs to be "in a stronghold," does that mean in a region containing a stronghold or does that character need to be in a siege in order to perform what the card says?
It means in the region.
Also, if a nation such as the North is on the last box before "at war" but is not active and the fpp has a card that lets that nation advance one step on the political counter, can the North go to "at war" or do they have to be active first?
Cards only break the rules that they explicitly override. If the card doesn't specifically break the rule that a Nation can't advance to "at War" when Passive, then it cannot advance.