Would it be possible to make terraforming work in a manner in which Any world non terran could be made terran in X amount of time? and rapid terraforming do it in say 2/3rds the time?
The X amount of time part probably isn't possible in the way you're hoping with v0.3.13. You could make a building or tech, which will require at least X time to build or research, that makes all planets of a certain type change to another type in systems your empire owns. You could perhaps use the add special / remove special effects to have a chain of specials that act as a countdown, which remove themslves each turn and replace with the next, and have another tech / building that requires the last special to be present on a planet to work. Putting the specials there in the first place could be dependent on the system containing an object your empire owns, which would probably be a ship in most cases for the first special in the chain.
As pd notes, there's no way to specifically target an individual planet, though. At best you can do something like above, with targetting planets that have a special or are in a system that contains something else that's targettable with a condition.
In future versions, it will be possible to give effectsgroups to ship hulls or parts, which would work in any system where you place that ship.
Habitation domes.. They provide Hostile + worlds with + 2 population. The only problem with that is you cant colonize hostile worlds. Its a very self defeating Tech though I assume something is in the works.
I think Hab Domes only work on poor and adequate planets, not hostile, in v0.3.13.