People, we really need some fun in here - and I like your ideas, they made me smile a lot.
But anyway, with the fandom atmosphere being heated up as it is, you'll easily be misunderstood. Then we have the whole traditions vs. artistic license debate rolling again....
So, let's be reasonable:
Kilrathi architecture: There is a lot of descriptions of Kilrathi buildings in Freedom Flight (the novel), and you get the general idea of theis aesthetics from some of the game intros (WC2, WC3). In general, they seem to like asymmetric designs with long-drawn lines and sharp edges. Somewhat like art deco, only "harder".
Clothing/style: There're also some passages in the novels - from what I recall, it's between practical for uniforms and flowing robes for formal occasions, but I might be wrong here. But I'm quite sure if there is a scene in Freedom Flight when the authors describe some Kilrathis civilians.
Kilrathi look: I don't think we need to argue about that. The games tell us how they look, and that they are an alien race that only
remotely resembles the terran species family of cats. The whole "kat" thing is a human strategy to familiarize the unfamiliar, and even to make the enemy less fearsome (as in "Charlie", "the Krauts", etc.).
Kilrathi civilian ships/traders: Blanketyblank. Brad?
Kilrathi trade goods: That milk and catnip thought is pretty funny, but in all earnest I fear that you'll get court-martialed for that. There definitely are Kilrathi beverages, like Arakh Tea - see the drinks list:
https://www.wcnews.com/articles/art5.shtml If I do recall right, there even is a Kilrathi drug.. but I might confuse this with Arakh leaves.
As for the sign: Someone somewhere had a Kilrathi font, so you can put up signs in Kilrathi lettering all over the place. Wait - got it:
ftp://ftp.wcnews.com/files/other/viner.zip
Female Kilrathi: I searched the forum, and they are mentioned quite a lot. Some appearances:
* Sivar Priestess in a Secret Missions 2 cutscene.
* The Kilrathi princess in two WCA episodes.
* The art of at least one of the CCGs 'Luck' cards.
* In the "temple artwork" in the WCP intro.
I haven't looked for a picture, but anyone who has access to those sources might go and grab a screenshot.
And for the whole thing - people will still argue that Kilrathi won't open bars or let people land on their bases, because the concept of intercultural trading is alien to them... - but in my eyes, although this isn't documented in the canonized game world, it may not deny the canon either.
I don't really know - maybe there are some renegade kats who want to trade, but they have never featured in the games...