A world filling up with people: We welcome commerce and negotiation!

Now I have these lofty goals and ideas.  I have made several RPG systems, and a few card games but I have not tried to make a board card game, especially one that we intended to publish.  The map started as a bi-fold 24 by 36 inch monster.  It was looked a lot like a Pangaea map of earth (very unintentional), it had 62 states divided among 6 countries. The continent was surrounded by over 100 hexes of water, with three islands. Verdan was going to me monolithic.
I next set out to generate the population for Verdan.  I knew I wanted assassins, and rulers, but I would need military forces of varying combat abilities and costs. My question was how to moderate the speed at which these fella’s came out.  I wanted things to ramp up fairly quickly, and with all of the available resources I knew that I needed to watch out for the exponential increase in resources as the game progressed.  The idea was simple.  Each card would have a fairly low initial (or inception) cost (IC), and a maintenance cost (MC) to keep the piece in play and under your control. Thematic The Facebook pageally, it seemed logical that you would have to be able to feed or pay these soldiers under your command as well. With all these resources going around I wanted to be able to share them between players.  I wanted a system of commerce and reasons for one nation to share its affluence with another, but how, and why would they?
I came up with the idea that a player would have a resource pool that would expire in the very first phase of his turn.  Then during the second phase you would collect resources from your states, and keep them until the very first phase of your next turn.  That would be the first encouragement to negotiate. If you did not use these points you would lose them, but I didn’t want points flying around between the players all haphazardly.
I needed non- military units that would serve as negotiators between two players.  You would have a negotiator move into an area controlled by another player, and that would allow the exchange of resource points. The Merchant and Diplomat would born as a direct result of this.  I still lacked a real reason for players to want to exchange resource points.  I knew that some players would support others out of friendship and more strategic minded players would wait for a player to get weak and then pump resources into him so that he would be more resistance for a different opponent attempting to take him out, but that was not enough for me.  I wanted something more, I wanted prisoners.
Actually, I wanted prisoner exchange.  I came up with the idea that if a unit was defeated in combat an opponent could choose to take them prisoner and keep them for ransom or vanquish them from the game. This would come in helpful if a player lost his ruler or other valuable card that might be hard to get back into play. Now there are reasons to negotiate, later I would come up with one more reason. The last could prove to be the most valuable reason to have a Merchant or Diplomat in your arsenal.
I knew I wanted the diplomat to be able to negotiate, but I wanted Merchants too.  Thematically I wanted the diplomat to be harder to kill off but weak in a battle, so I limited the types to characters that could harm him or her.  The Merchant was a different story, it needed to have the negotiation of a diplomat, but also needed something more to do with economics it self.  The merchant became an asset to both players giving them a slight resource advantage, but was able to be attacked by anything on the board. Merchants and Diplomats had another nice side effect.  Another target for assassins! If two player’s negotiations hurt a third player, that third player could always send an assassin in to do the dirty work. If you kill the negotiator the negotiations stop. What if I don’t have an assassin and I have a need to get an opponents card off the board? Can I pay another player to take care of that for me? The seeds of strategy have begun to spread.