Looking good so far, the red run off on the upper areas is a nice touch and the weathering around the tracks is good too. Watch the white areas, on a couple you seem to have either yellow showing through from underneath or yellow interferance from a spill (top central white bands) on some of the others you seem to have white bleeding into the edges of the yellow (back and front white panels) also howcome the middle white piece hasn't recieved the same grey shading as the others?
Very impressive freehand work, though i would be tempted to redo the moon, the black on bone makes it look a lot more cartoony than the earth, browns might give a subtler shade definition for the craters.
in a fluff note, earth int he 41st millenium has no oceans..they were burned off even before the horus heresy.
Great skin tones and a nice variety of hair colours, this'll really draw eople to look at your army.
Looks like you've got your work cut out, looking forwards to seeing this lot get completed.
On a personal note i would be tempted to add some trophies or pieces of armour to the bases, i always find grey bases never look complete and always seem to make the colours on a model look a lot more dull then they really are. a couple of points of interest from som dead grass or a smashed hemet will really make them look more complete.