My main complaint about GF is the fact that you can't decide how many crystal and metal astriods are in a planets gravity well, what the max population/logical/tactic structures of a planet are etc etc.

I'm afraid that no matter what upgrade they give to the Galaxy Forge, this will never be possible. The reason is that the maps do not determine the number of Asteroids, the Planets do. That's why even the premade maps always have random resource asteroids. Now this is fairly easy to change in a mod, but that would make the resource asteroids standardized on all maps, for example every ice world would have to have 4 crystal asteroids or whatever change you make.

Okay, you're not really making much sense.

Do you want to control how many resource asteroids are on a planet or do you want to leave them random like they are now?

If you want to control them, you have to create a mod and edit each planet's entity files and change the counts that are allowed, but like Goa said, when you do this, all ice planets will behave in the manner that you've specified.

So if you change the entity to have matching min and max resource asteroids, say that Volcanic planets have 3 metal asteroids, then all volcanic planets on your map will have 3 metal asteroids, period.

If you leave them as they are now with the min being something like 2, and the max being something like 4, then each volcanic planet that's in your game will randomly have between 2 and 4 metal resource asteroids.

You cannot do specific asteroid counts on a per planet basis, the game is unable to do this.  The best you can get is a per type basis.

This goes for all of the planets.

Edit:

And the same goes for population, tactical slots, logistical slots, and emergency facilities upgrades (Planet health).  You can change it, but only as specifically as the planet type, not individual planets.

Of course there is.  There's two mods that added planets as well as sizes, namely Sins Plus and Celestial Bodies, as well as several other mods that integrated both of those into them (Distant Stars being one of those), and a few more mods that have made their own types (Maelstrom being an example of that).

Does Galaxy Forge work for these mods?

Yes the forge works with them, just copy the galaxyscenariodef file from the mod into the forge folder overwriting the one that came with it and you'll have all of the pretty options that come with the mod.

Gas Dwarf, in reality, yes.  There are gas giants that are larger and smaller in size.  We just don't call them anything other then gas giants.

I would think so provided it does nothing else, only way to tell is to try it though.