Every building and unit has individual running costs in resources (gold). Those costs have to be paid in regular intervals (e.g. like every 10 minutes). As soon as the object is demolished or destroyed those costs are deleted. A company building lacking according resources for production or a unit standing around with no orders (what units will do most if the playing time) will still need the full runnning costs as an object in action.
The only way to decrease running costs is to decomission the building or unit.
None so far.
The costs are deducted automatically.
Running costs might be part of first milestone.