i'm not so sure this is needed. i agree with most of the things you all are saying, but why artificially limit ship construction potential? with differently-sized shipyards there will probably be a restriction that only the bigger yards can build ships, which is fine, but i don't see why limiting the number is also necessary. if you want to put 12 battleships in the build queue, go ahead. that just means you'll have fewer resources to devote to more critical areas.
also, i'm sure there were some shipyards that were capable of working on more than one cap ship at once. if you make a limit, whatever it is, people will complain "but shipyard X built way more ships than that all at the same time!"
also, i don't know if gearing limits are in or not, but i think they are a wasted effort as well. several combatants in WW2 were forced to convert civilian facilties to wartime production very quickly. entire factories were moved, people built planes and vehicles outside when their factories were being bombed, infantry weapons were made in basements, etc. etc. once again, if you choose to focus your production in one area, a well-balanced opponent will crush you (assuming the game is able to use all three unit types ably).
delaying build time due to bombing runs over the target province or factory is a cool idea though.
//just my opinion
-chris