Wow...it took me QUITE a while to sift through it but I think I have a solid grasp on it. But I dont think I could adequately explain it here.
The 'spaces per one' refers to how many of that item it will place in the ship on that particular run through the design queue. For example, if spaces per one is set to say 200 for shields, it will put one shield generator on for every 200 ktons of ship. I DD(300kt) would get 1, a CL(400kt) would get 2 and a BC(600kt) would get 3.
The 'majority component' seems to be the only one used after the 'once through' of everything in the queue...ie all other items are only added once (using the spaces per formula) and then the rest is filled in with majority component.
The easiest way I found to test it was to go into the 'Tech Areas' file, change the 'Raise Level' on the items you want to test to allow the AI to have those gadgets. Start a new game at 'medium tech' to give the starting AI the gadgets you want. Hit 'end turn' for your start race once to give the AI a turn in which to design all its ships. Then go to options, players and turn the AI players over to human control. Go through to the enemy player's turn (now under your control) and check their designs.
I hope this made sense. I understand all this stuff, but cant really explain it in writing.
Talenn