1) The issue with free maintenance in PDC hangars goes away in C# due to the removal of PDCs.
2) While you don't pay maintenance on ships in a hangar, you still have to pay maintenance on the hangar itself. A 1000 ton FAC will probably cost a little over 100 BP and a hangar bay large enough to hold that FAC also costs 100 BP. Then you have to build the rest of the ship that contains the hangar and pay maintenance on that as well. Looking at a few warship designs in my current campaign, the costs are 125-140 per 1000 tons. So, if anything, hangars start to look a little expensive in BP / maintenance terms.
3) I agree that hangars are probably generous in terms of size vs capacity so I probably could look at adjusting that a little.
4) I definitely don't want a system where you have to launch or land parasites a few at a time. That would get tedious really fast and I don't think it adds anything to game play.
On point two I usually see about 100-120BP per 500 tons on fighters at around magneto-plasma tech level for an interceptor or missile fighter and around 200-250BP per 500t for a sensor scout. The thing with the hangar cost is that it don't scale maintenance with technology advancement.
On point four I agree that there should not be any additional micromanagement. I would suggest just adding a cool down when they land or tries to launch similar to when you fire a weapon based on crew grade. That would not add any more micromanagement than time to reload box launchers within a hangar.
Maintenance within hangar would not have to be a complex thing either, the parasites would just eat some of the ships supplies over time. I just don't like when things are completely free, hangars are quite good as they are with being a very dynamic and flexible system.
In my opinion it would not have to be complex or add much micromanagement just scale better. I also think it would be fun to design hangars based on my needs in the same way i design missile launchers and magazines etc..
I certainly don't expect anything done at this point, but I would like to see something done to make it fun to design hangars and carriers a bit more. Especially since you rarely need to upgrade carriers aside from their engines.