I thought that project was to be a remake of Shattered Steel? Though they honestly haven't given us much to go on, so it could be anything.
As for Liara.. I'm not going to rebuke you for saying Tali is my favorite (though Garrus is, oh man) because I am quite fond of her - but, comparatively, Liara just seems so... bland. Like I said, a bookwormy Asari who just /happens/ to become fascinated with Shepard because he/she was touched by working Prothean technology. I dunno about you, but, personally, that's actually kind of insulting.
I believe she had some character that honestly never reached potential because she jumped on the let's-hump-Shepard bandwagon way too quickly. It made any depth she could have had feel shallow. She was not Mary-Sueish, but in the first game she did really feel to me like little more than blue fanservice. And then to do a complete 180 with this odd, dark obsession of hers was completely OOC. That being said, I'm sure the reasoning behind it was expanded upon adequately in the DLC, but if you put Liara from ME1 and Liara from ME2 in the same room I would swear they were two completely different characters. Especially given that Asari are so long lived, I find it really hard to believe something could change her /so/ completely in that minute fraction of her life, without retaining any semblance of the socially awkward scientist she was before.
As for Tali, I can definitely see where you're coming from with the whole representation of her race and their strife thing. But I think a little of that is going to go for each Quarian, simply based on the society in which they grew up in. From the stage where they can be helpful, near everything they do is for the good of the fleet - there is a solid sense of kinship, and even if they are exiled it's not a value they can just magically erase. I would say that (almost) all Quarians are sensitive to race wide-issues, like their war with the Geth, or the possible retaking of their home planet.
I'm drifting a little off topic now, but keeping that in mind, the Krogans, in a similar sense, are a delicious contrast to the Migrant Fleet - they are being plagued by a genophage, but because of their nature, few of them can even be bothered enough to care.
Besides being rather an embodiment for the struggle of her race, Tail's got alot of traits that make her a really fun character, and I won't deny I find her interesting as well.
Which combat class did you take? I chose Vanguard for my first run and I've stuck with it since. There's an element of risk and fun in charging head on at a group of enemies instead of just shooting at them over a flipped crate. I get the feeling Biotics could also be really fun, but combining their powers is too strategic for me to bother with, and not quite so thrilling.