To add a few thoughts myself...
If we take seriously Xenology
's claims seriously, and in this particular case it seems reasonable to take it as a broad outline (though remaining skeptical of the specifics, naturally), the Tau are a mammalian race, possibly originally herbivorous ruminants, though the origins of the Fire caste in hunting groups suggests an omnivorous diet. In any case, that does suggest certain broad similarities with the human race and other primates. I see no reason why the Tau would not follow the same basic pattern as our terrestrial mammals, and so, like our races, their females would tend to be more lightly built and more flexible than the males. The degree to which they are may be less pronounced than in humans, but it seems to me that Tau females would look more 'feminine' than Tau males, by human standards of femininity.
As such, I quite like your pictures, Kaiizen. In a general sense, I would imagine Tau females looking something like that. Perhaps not exactly like that, but it fits the basic idea. I must say I'm pleased that those Tau women aren't over-sexualised - something this game is often at risk of. Some Sister of Battle artwork springs to mind, which is kind of creepy, as they're supposed to be chaste and modest.
That said, sexuality isn't irrelevant either. What Tau taboos exist and don't exist could be an interesting question, though I hesitate to proceed with that line of thought. Rummy, do you think we can handle a few thoughts on that?
On another note, Khemri mentioned hair as a status symbol before, and I'd be inclined to agree with him. One also has to point out that in some areas, particularly the Fire caste, long hair can be a practical liability. Contrary to the pictures, I'd guess most Fire caste Tau would have shaven heads or keep their hair closely cropped. The Tau are usually represented as a quite pragmatic race, after all. Perhaps as time goes by more ostentation is allowed, for ceremonial purposes. Speaking of hair, any hints on colour? Most artwork we see sticks to plain black; is that all of it, or would Tau have a greater range of colours? They're advanced enough to have invented hair dye, if worst comes to worst.