Economy part 5

Question 5 is as follows:
Do you need an NPC economy? That is, where does the iron for swords come from? Dwarven miners? Are these NPCs? What about flour from bread? NPC farmers and millers? Who farms all those cabbages? What happens to them once farmed? Who buys them?

I feel like I answered a lot of these questions in previous posts, but it doesn't hurt to rehash this.  I hope to have as little of an NPC component as possible.  Payment for services rendered is about the only area where NPCs will be involved, and that can be a nice 2d screen.  Determining what services rendered get what amount of credits might be a difficult task as certain statistics for each player will have to be tracked, such as amount of time spent in the field and amount of damage a player has done to enemy players.  I really want everything else to come from the players themselves.  Because plots of land do not reset with winning conditions, and players will still retain the skills they have learned, players will still have a sense of permanence in the game and the economy will get back to where it was very quickly.