Don't forget the Crish who are basically a race of
Big Guys crossed with
Big Eaters, but that may not have been as clear.
I can answer the question about the Maki-Liki and it's no, they do not live up to the reputation, or at least most of them don't. The idea I had in my head, but had trouble conveying in a quick elevator pitch, was that most of the really famous Maki-Liki to the Galaxy at large ruthlessly used their sex appeal, grace, and voices to climb the celebrity ladder and then stay there. This was typically done with risque behavior and dress, suggestive dances, like the tango, and "scandals" that were designed to titillate and keep them in the spotlight. Most Maki-Liki resent that reputation almost as much as they resent their occupation by the Ascended. It doesn't help that the Ascended encourage the spread of that reputation to undermine the efforts of the Maki-Liki to free their homeworld. I guess you could say it's a little of A and a whole heaping lot of B.
The Morsk, well, I think the short answer is no, they don't treat their scientists that way. They have a clannish structure and as long as you are able to protect yourself and help the clan, they respect you. If you can't however...
I'd have to think more on the Syrens. Part of my problem is that their a darling. I've had them bouncing around in my head in one form or another since I was in junior high (2002-2004) and I've never had to really nail down how they differ from humanity beyond the cosmetic things. The Morsk have been around just as long, but their current incarnation came about junior or senior year of high school (2006-2008), and part of this incarnation's culture has always had a strong clannish vibe, which may have been why they are so much better defined in my head than the Syrens.
I hope this isn't sounding defensive. I just thought that laying out my thoughts would help in getting things nailed down.