Lookin at the model as far as construction goes first of all there are few bits you might want to consider.
With the soft polystyrene layer it will be difficult to get a lot of stability for the Kan when you pin it on as the plastic base is hollow.
While you still have the chance:
1)work out where the can will be when finished.
2)run pins down through the polystyrene and through the plastic base so there is about one inch sticking into the hollow area.
3)stick big blobs of green stuff to completely cover the pins and attched to the top of the hollow area.
This will help stop this finished model \"wiggling\" on the soft poly.
As far as painting goes ther are others on here better to advise you than me. But if you want the piece to appear filthy and weathered you might want to start with brighter colours before knocking them back with washes. This would help the model stop appearing too dark and monotone.
Spacemunkie is probably a good person to ask as i seem to remember a few of his pieces with excellent weathering.
Good work on the checks though i definately lack the patience to do that sort of thing, im easily distracted :drunk:
Im interested to see what your planning to use the void on the lower part of the base for. Is it going to become a mini-diorama?
Hope any of this was helpful if not ignore me

:drunk::drunk: