Is it possible to use the race bonus from the aforementioned races to boost the resources of planets owned by your legion mates (provided they are also in your planet database)?

No, but you could get them to abandon the planet and boost it for them.

Easiest way to do that for a legion mate is for them to share an UNOCCUPIED planet, you colonize it, boost it to the desired level, then one of you leaves the legion temporarily while your mate invades it.