Yes. The Catanian rules system defines a stack as a place where cards are located or were located. Therefore, if a stack was completely depleted during the course of the game, it continues to be a stack and can be used to deposit cards there.
On your own discard pile.
Yes. Once you have chosen a stack and looked at it, you also have to draw a card from it.
You may combine city expansions and settlement/city expansions at will.
As long as this doesn't have effects other than purely optical ones: yes.
No. Either both players receive one resource each (if they don't have any skill points at all or an equal number of skill points) or only the player who has the most skill points receives one resource.
You are entitled to the resource if you meet the requirements for the "trade advantage." The trade token serves as a reminder of this fact. The same applies to the hero token.
No.
Yes.
No.
Yes.