Highest diplomatic finesses and trading centers

I think it would have been very cool if at highest diplomatic levels you could send special sabotage mission against a town which automatically fails but if the targeted town's counter intelligence and interrogation aren't high enough it thinks the attack come from another town. You know, to raise one town against another, like some murder in 1939 which started a war

While i'm here, i would ask to make something to favorise tradings, for those people who'd like to have a 'merchant' town. The first thing to do is improving the trade filter, it's nearly unusefull as it is now. I've also thought about some central trading centers where people can put things for sale, like in an auction house, but only for gold and with some tax by hours it stays there(so people will want to sell it fast, balancing their prices) and a time limit(so you pay the tax in advance and when your wares are sold, the extra money comes back). You still would have to transport wares to there, but your caravans come back afterwards and the trading counter will send carravans to give your money. Everyone would have access to the list of wares from his town but it would use a messenger for each consultation. It would also have a price historical(which would 'stabilize' economic). When you buy ressources, you send your caravans with the money and the central send its for the wares
When your town's marketplace, storehouse and warehouse are level 20, you would be able to build some building in your town which would do the same kind of feature but with part of your town's caravans and reserves(you set it, as %, with extra caravans and stock with each upgrade which can only be used for those tradings). You would also fix the tax people have to pay to use your trading center, which would be added to your gold.

It would also be great that an alliance leader could build an administration building which would help the alliance's exchanges, reinforcements, and so on....Don't really have a clear idea on how to help with troops but something very expensive only a big alliance could build, which would be very usefull for all its members and with a storage where members can send extra ressources which other members can take(limit per day fixed by leader). It would also have to be placed outside a town(to avoid some problems like 'this guy don't log in anymore') but could be attacked and taken by other alliances, meaning it would have to be defended but any members of the alliance could send in troops(new strategic option :D). Upgrades would act like Walls for your town and add stockage capacity, using what's in its own storage(full-10% for next upgrade)