On the subject of aircraft, I'd like to see a little more differentiation between the torpedo bombers and dive bombers. I was thinking maybe increase the bombardment ROF for Torpedo planes (making them more likely to get in a lethal hit) but make them -1hp, to reflect that they were very vulnerable to enemy Combat Air Patrol and AAA, because they had to fly basically straight at the target, at low altitude. Not sure if that's the best way to go about it, but right now they are too similar. What do you think?
Also, regarding the buildings, be careful, because if you flag them military (allowing them to be built in Mobilization), the MIL-trait civs will get them for half-price, it works off the same flag. The only way around that (that I know of) would be to create a new Factory improvement, based to either a tech or resource that only the MIL-trait civs have, that has the same effects and costs double, so that when it gets the 50% discount, the cost is the same. But that could be more trouble than it's worth. I'd recommend leaving it, and accept that if your core cities are getting bombed, you will lose production, if you chose to mobilize. That's part of the risk of mobilizing.