I got a little late on this tread, so let me try to get to the points that actually matter (cause discussing physics with numbers about a technology that doesnt even exists seems quite useless to me)
Ships follown in 2684, in the case of privateers, we could very well see old confed fighters. You see the militia/insys seems to fly in wcp excals and tbolts. Pirates may have tbolts, sabres, arrows, and, who knows, maybe even a lower model of an excal?
the other governments would indeed make their own designs. the thing is, those fighters in the games we fly are not the only ones that exist in each game time, just the ones used in the sector/ship. I have created a whole bunch of the independent nations of my wc rpg. Though it happens in the end of the war, its still an idea to follow
On the UBW keeping dragons or giving them, the most probable would be that UBW would give the dragons back in exchange of something, like tech, money, trade deals, ships, etc
Politically, the UBW was giving it back to be nice, and Confed gave whatever to thank their nice fellow neighbor, while actually its simply trading
The Dragons may have been made with Confed money, but it was also confged confed money that was used to kill thousands of UBW citizens. You think the UBW would nicelly give it all back? If you didnt notice how the UBW people are, their feelings towards Confed and its citizens, you should play wc4 again
In the end, its all a work of diplomacy and PR
on the Dragon's maintenance, indeed, newer tech and higher price doesnt mean more expensive maintenance, but in the case of the Dragon, it is a very advanced ship with a hell lot of new tech. Most of it, UBW (and even confed in general) wouldnt have the infrastructure/tools/training to maintain, which would give in there an extra cost to prepare it all. Now, think of how many dragons the ubw had, and if it is economically feasable to spend so much money to train people, prepare places, adquire specialized reports and equipment to maintain so few ships.
The UBW would most probably, as mentioned before, check it out as much as possible to "adquire" the new tech, but in the end, the dragons would be handed back to Confed, after some negotiations, of course
K