Yes you can do both. You can set up (as a steward or a Lord) to bull/sell x food at y cost. In this case the money for buy orders comes from your pocket. You can also set up the region to buy/sell food at a price once a threshold is meet, in which case the trade balance is used.
Nothing is stopping a steward from setting up buy orders that could potentially bankrupt the region, that is why picking a steward is a BIG trust decision. Then again there is nothing stopping a steward from setting up manual sale orders and pocketing the gold.
Wait--how does the steward pocket the gold, other than through his tax share?
