Terraforming alterations

Gas Giants: 

Current science speculates that gas giants have a molten rocky core, on that note I would love to see the ability to terraform them into a lava planet, losing one size during transformation:

Large gas giant = 1 medium lava planet after transformation

Huge gas giant = 1 large lava planet after transformation

Could always add resource requirements to terraforming them (eg: 10 Quadrinix, 10 Orichalcix for large, 20 Quadrinix, 20 Orichalcix, 20 Adamantium for Huge)

More terraforming choices

Ive noticed there doesn't seem to be a way to downgrade a planet like you could in ES1. Would love to see the ability to downgrade a desert planet to lava planet, or even cross terraform a terran planet to atoll, forest, or ocean planet (or vice versa) as long as the player has unlocked the corresponding tech.

Artificial Planets

The ability to create small or medium planets from debris that naturally occurs within a star system would go a long way to mitigate systems that have only 1 or 2 planets in them. Generally, 1 artificial planet per system, and make it cost a lot so is only viable later in the game. Also, artificial planets could have around 75% FIDS as their naturally occurring equivalent counterparts, no strategic resources, 50% chance to have 1 or 2 negative anomalies