Shas are actually hermaphroditic from birth (2nd edition revised, p. 92-93) with a period called the Dheviis, just after their equivalent of puberty, in which they (individually, consciously) decide what their gender will be. This is irreversible so no, it's not convenient camouflage and it's a meaningful gender definition. Just not from birth on. (There's actually a few terrestrial animals which do similar things in the reptiles, somewhere I believe).
Shas actually obsess over gene-therapies to adapt members of their species to different situations (again 2nd rev 92-93, get the book!

) which is probably which makes different units look so different from each other too.
The exrah are basically your stereotypical evil space corporation (to the point of boredom,
IMO) without much of a twist to them
The thing with the
EI is that it leaves subservient species (partly) to do their own thing, as long as they aid in it's own quest here and there. The
EI wouldn't care much about 'interstellar capitalism', that's just something it's fine with the Exrah doing in their spare time