[Skulky]

The idea of a non-respiratory race seems interesting, they could have a reduced max population but be able to colonize all planets from the start. They would have an atmosphere that is on no planets so they would always have to build domed but would be given the colonizing techs as part of their racial trait. This would put new emphasis on capturing other races to colonize with.
I would go with the Psy-Hardended race personally, in the later game the ability to move without certain components can become outmoded if the player uses repair bays or the special components that repair by themselves. The Psy-Hardening would help you against those allegiance subverters but you can just put a master computer on in addition to crew and bridge and i think that will solve taht problem, i'm not sure but that was what i think was happening in the Homecoming scenario, which btw everyone should download, i'm still in the process of beating it, its hard when you suck so much and there are all these big powerful empires around you.