JMSx2, congratulations on the new coach. We have had ours a couple of years and really enjoy it.
On my 2005 Land Yacht, the water pump, fresh water tank drain, and hot and cold water drains are behind the door at the foot of the queen bed.
Be careful removing the plastic plug in the water heater. It is easy to round over the corners. After the water heater tank drains, there will be close to a quart of water remaining in the bottom of the tank. This needs to be flushed out to remove calcium deposits left behind in the water heater. The bypass valves for the water heater are accessed inside the coach beside the water heater.
As you winterize, don't forget the filter in the faucet at the kitchen sink.