Redundancy
On your initial HW, you have a spaceport, but also a cargo shuttle station, an ordnance transfer station, a refueling station. Am I right that the OTS and the RS are redundant with the spaceport? As for the CSS, it doubles the load/unload speed, right?
Other questions
Is an ordnance transfer system mandatory to transfer MSP and/or missiles to a ship?
Same question to a colony without any facility?
Is a cargo shuttle bay mandatory or does it just speed up transfer?
What about a fighter can it transfer fuel without any extra device?
Yes spaceport makes the cargo, ordnance and fuel station all redundant
Yes, the ordnance transfer system is mandatory for a ship to act as a collier for the fleet. The ships receiving the ammo need not have one - only the supplier needs it
The ordnance transfer station mandatory in order for a colony to act as a rearmament point
The cargo shuttle bay speeds up transfer for freighters with cargo space. This module also allows a freighter to trade with colonies that do not have a shuttle facility of their own.
At least one shuttle bay is mandatory on ships meant to carry and transfer maintenance supplies to other ships.
A fighter still needs a refueling system in order to transfer fuel to other ships. However, unlike other ships a fighter does not need for a colony to have a cargo transfer system in order to take or give cargo to the colony as it is assumed to be capable of landing on the surface itself.