Anyone work these out?

The devnull mod has research departments for bases. I tried using them once and they failed. There's something about only being in orbit of a colony I think.

In SE4 captains were a component, for the Star Trek mod I think.

Space Labs will only contribute research if they are in orbit of a colony.

You can do Captains/Admirals as components. The nice thing about SE5 is that you can have different scopes, so while a captain component might improve a ship's combat skills - an admiral component could boost all ships in a sector etc.

Space Empires Depot | SE:V Balance Mod

You can make captains as a Unit Type (like troops) and edit UnitTypes so that type of unit gives it's abilities to the ship carrying it while it is cargo... unfortunately, it will also give it's abilities to planets while there... and starbases... and all other units of that type will do the same (so if you use troops, all ships carrying them will gain the bonuses of troop combat sensors, and the ability to fire troop weapons that have space ranges

EDIT: I'm unsure if you can use UnitTypes to add entirely NEW categories of units...

You can; just copy an entry and make a new one.

SpaceEmpires.net | Space Empires Wiki

If you do make the troop thing it might be advised to set the ability to one per... and see if that works to prevent the bonuses stacking/being applied to the wrong thing, if you can manage it, not tried myself but it could work maybe.

Generally bonuses like that are one per in the system coding. Nothing really prevents you from building multiple Mineral Scanners on a planet, but the bonus from them does not stack because the facilities have the same name. Same would go for Captains as a troop type.

Such abilities do not stack because its the same ability, not because the facilities have the same name.

SpaceEmpires.net | Space Empires Wiki

Same ability and same scope then... I know Mineral Scanners stack with the system version of the same ability. So the only way to get them to stack for captains would be one to have Space Object while another had System.

Wait... would that mean a galactic research bonus from a Cultural Achievement would not stack with a galactic research bonus from race or a galactic research bonus from government type?

The item adding the bonus must also be a factor - so a facility bonus of a specific scale would not stack with other facility bonuses of the same scale, but doesn't preclude a component bonus from cargo that applies to parent of the same scale...