As for the "life forms", that probobly just means a small chance of there being single-celled bacteria, not very complex(or is it???).
Well they don't kow about the magic material deep in the earth, so how are they expected to know everything. Hell, They don't even believe that GCS exists!
The place has magma, which pretty much completely in one stroke solve the heat problem. Better still, it is mostly underground, allowing for us to heat water with minmal chance of !!FUN!!. Another, possibly more crucial point is it has water underground. Sure, by water I mean "water-saturated clay", but still, we could distill it. Or we could set up a auxilliary putpost in the far north for importing ice, and melting it down with our magma. And with your air problem, your solution is to go to the moon? Where there is lots of air? Never! We will import air in the begginning until our plants could allow for sufficient replacement from our carbon intake.
The oft-mentioned "muscle weakening" which is common in low-gravity eniroments would be irrelevant since we're all clearly working our ass off/training for war.
Also, trading is limited, as i believe the time is 4 years from earth to mars and back. Clearly, we need to make it worth their while.
While I was typing this, a thought occured that the current problem with space traval, mainly, little use and massive costs, could be avoided if they send us stuff and we send stuff back. Until we rebel, but it will be pretty good for earth, until that point.
What about relatives? I want some of my relatives along, as well as other people. We ned to set up some system, a majority of DF palyers is needed, excepting the neighbors/laborers. Plus it'll get all sad when people want to go but relatives want to stay. It'll end up like the migratory master weaponsmith and his family of cheesemakers, but on a far more expensive scale.
EDIT: Sorry, in the night my spelling skills suffer.