In Age of Asteroids, resources are spare so everything you see is highly modular to be efficiently constructed and transported.
Therefore ships will be unmanned. The pilots wil sit in their Command Simulation Pods on the Surface and controlling the ships from there. So to maintain a distinct fleet size you'd have to maintain a distinct amounts of Simulation Pod Modules. This way it is not needed to have life support on every ship and the ships are more nimble.
There will be 3 classes of ships:
Class I ships
Primarely there are the Orbital Fighters and Scout Ships. While you will use scout ships to search the space around or getting surface samples from other asteroids (or looking out enemy colonies) you will use the fighters to protect your colony or to engage other asteroids. Those ships are able to do asteroid transfers but cannot be used to colonize or transport anything.
There will be Equipment slots. For those Class I Ships, you can have 1-2 slots depending on the ship. Beside the weapon of the ship you can choose to give the ship extra power, extra speed, turnability a shield or space/surface bombs to attack colonies. A ship cannot use Blaster Weapons to engage buildings.
Class I ships can land in underground hangars.
Class II ships
Class II ships are bigger than normal Fighters and therefore are able to carry more equipment. They will not be able to land in a hanger, and therefore cannot be build on the surface. You will need to build a spacestation / spaceport to build and to maintain them. They also use more resources to build and need more time to be crafted.
Class III ships
Class III ships are the big ones. Transporters, Colonizer and Battle Ships can only be built at orbital spaceports and need a lot of time and resources. They can carry differents things like ore, colonists ore - in the case of a battleship - a huge amount of weapons. Transporters and Colonizers are merely unarmed, so in case of an attack you may send them away to keep them out of fire.
Class III ships are slow and can hardly be maneuvered - to acommodate this drawback, Battleships are equipped with heavy defense weapons like the defense towers of the surface. In a fight, Battleships are stationary to transfer all of the energy to weapons and shield.