Galaxy Forge help needed

Hi all. I'm relatively new to the community, but I've already fallen in love.

That said, I've managed to figure out most of what I need to make now maps, both through the few available tutorials for the Galaxy Forge, and through my own experimentation, but there are a few things that I simply cannot figure out, or find an answer for. I'm hoping someone more experience/knowledgeable about the 'Forge can help me out.

I want to make my own militia units for a few maps. Primarily just swapping out/adding a few units to the militia that spawns with the planets at the beginning of the game. Such as an Advent, or Vasari Militia instead of the normal TEC units. Perhaps even adding a defense structure or two to some of the better worlds.

Also, with the Outlaw Sectors DLC, I want to change what units spawn for the roving militia's, preferably to match the units with the ones that originally spawned there.

I also want to do the same for the pirates, or at least their home units, to make their bases more challenging on the maps that I create/Modify, such as by adding a starbase or a Titan to their base.

I would also like to add the roving militia mechanic to the pirate base, but using pirate units, for near constant small raids, and/or reinforcements for the base.

Can all of this be done in the Galaxy Forge, and if so, how do I do it.

Note: I'm not really ready to do anything to the game code just yet for modding.

As a side note, when manually placing resource asteroids around a planet (and presumably units as well, though I haven't tested that), the Y and Z axis are swapped on the UI in the Forge. Placing them 'north' or 'south' of the planet in the forge, makes them spawn above and below the planet in game, instead of around the equator line were structures are normally built in game. This is easy enough to fix manually to make them spawn in more normal areas and is still playable without fixing, but it is very wonky looking in both the forge and the game.