If I may, from my understanding (and this way I might be corrected if I am missing something):
- Launch ready ordnance is used to deploy engineless payloads, such as buoys or mine platforms.
- You assign the launcher to the control and the payload to the launcher in the "Ship Combat" Tab. I don't think you need to open fire with the control, but I might be mistaken
- You select your target in the orders tab (the target can be anything and is not limited to waypoints)
- You hit the "Launch Ready Ordnance" order
- Your ship moves to the target and deploys the payload once
- Open Fire is used to launch self propelled elements that you want to deploy from afar (missiles or remote deployed buoys for example):
- You assign the launcher and target to the fire control and the payload to the launcher
- The target must be either a (hostile?) contact or a waypoint
- You hit Open Fire for the fire control
- If you are in range, the ship will automatically fire your payload, though I am unsure whether it does so at your fire control range, your payload range or the shortest of the two (I would expect the third option). From what Steve wrote previously, I assume that if you are firing at a waypoint it only takes the payload range into account.
- You don't need to issue any order (except a movement order if you are out of range), but don't forget to cease fire on your Fire Control or it will continue to shoot as soon as it is ready