The gas in CBM is "held in place" at a molecular level through...

The gas in CBM is "held in place" at a molecular level through adsorption to the coal and through water pressure, the latter ensuring that the gas molecules stay there. Remove the water pressure and the gas will be released and available for production. In many cases a significant amount of water needs to be produced up front to ensure stable and consistent gas flow, so first water, a sufficient amount to decrease reservoir pressure, then gas.
if there is strong aquifer support, ie aquifer replenishment from elsewhere, even more water, or at a higher rate, needs to be produced to lower the pressure.
A production test can prove permeability and producibility. First water production and then hopefully gas if the test lasts long enough. The water rate can also be used to determine permeability and converted to gas permeability.
Coal seams may have fractures, butts and cleats. These provide connectivity in the coal seam reservoir, and permeability, hence water and gas rate. High flow rates may damage the coal face, causing a well to produce significant volumes of fines, grit, sand and coal particles, This may cause problems but generally can be managed, limit the flow rate especially in the beginning.
The distribution of these fractures can be fairly random, some may connect, a lot may not. Hence pattern drilling, a lot of wells to capture the randomness of the coal properties, some wells will be beyond excellent, some average, some actually may just fail to produce at all, it becomes a statistical exercise.
Does the water pressure need to be controlled, absolutely, it needs to be decreased. As far as I am aware, the lower limit is dictated by where coals start to swell, coz when they swell fractures start to close, bad news for permeability and flow rate, but as gas is produced, losing molecules, coals shrink, good news for permeability and rate. As you can see from the above, a lot of moving parts, but all manageable. 'hope this clarifies the water bit of the system.