And is it possible to Limit the Returning armada titan to just 1 active at a time? Perhaps making an ability that can't be used while a ship is alive
Sort of a piece of cake. You can do it multiple ways, not sure what GoaFan77 is doing specifically.
To limit it, the first thing you need is for the spawning entity to be unique. It can't be off the Titan factory for instance, you can build as many of those as you have room for. The easiest way is to spawn a unique building for each faction at their homeworld on game start, something invincible, incapturable, and otherwise irrelevant.
From here, you have multiple options for making it unique, the most foolproof one I can think of off the top of my head is doing the buff file in two stages. The first applies to the spawner, and disables abilities, this prevents casting further titan summons. Of course, the buff also summons the Titan, and applies a post spawn buff, it should finish on OwnerChanged. The buff on the titan needs to send another buff back to last spawner using OnBuffFinish for the trigger, and finish on OwnerChanged. The buff you send back should be a simple RemoveBuffOfType, negating the original application and freeing the building to construct again.
Without multiple abilities or spawners, specific counts get more difficult. I'm too lazy to try and figure out a solution for this right now, so you'll either have to wait for him or someone less lazy and or smarter than me.
Your other two questions are Yes and No, in that order. I agree with the wish for a constant.
Edit: I type too slow...