Testing, look at the aircraft carrier, helicopter carrier and fleet command as mobile bases, just like the bases you might have in you country.
NFP obviously go on aircraft carriers, navy helicopters on helicopter carriers. The cruise missile ships, nuke submarines, frigates etc go with any carrier. Likewise all defensive batteries go on any carrier. Fleet command can also have all these things along with them, increasing your attack capability, except they do not host any type of aircraft.
Personally, I think there are going to be some upgrades/changes to the navy before too long, so I would hold off before going big on them. And at the moment you cant upgrade the aircraft, so they take a lot of losses, but are ideal for fighting anywhere on the map.