This was a big post with a lot of thoughts, so I'm gonna break it up a bit...
Xandurpein wrote...
For hundreds of years Quarians have hidden their faces. With humans nothing our faces communicate a lot of our body language. In quarian culture you would normally not search the persons face for clues to body language. This made me wonder if one of the reasons it takes so long for Shepard to catch on to Tali's feelings is that she may never seek eye contact with him.
I imagine that, yes, those sorts of cues would be altered for Quarians after living in suits for so long. It is a good explanation, I suppose, to cover for the real reason it took Shepard so long: because Bioware took the Tali romance out of the first game because they thought people wouldn't like her XD
Oh, and MaleShep is Male, and guys suck at reading body language. Kelly is human, and she catches on pretty damn quick.
For a quarian to show her face is an act of very deep intimacy. The reasons are medical, but it would also get a cultural meaning. To a Quarian getting used to the other races would be as for a human trying to get used to walking in a nudist camp. ... when she does begin to get feelings for Shepard, maybe it would be a source of embarassment to have Shepard 'flaunting' his face openly.
This point I don't really agree with. Frankly, I think Quarians often hate their suits. Their suits are only there because of the hardship of living on the ship, and they live on a ship because they have no home planet. Tali is clearly upset by the fact that she can't just take off her helmet and look Shepard in the eye. While it is true that sharing their faces with someone is an act of intimacy, I don't think it necessarily follows that seeing someone's face is a taboo the way that nudity is. I think they find it frustrating that they can't do it more openly.
Casual sex would be something unheard of in Quarian society. Sex, or any physical intimacy at all really, even between two Quarians is a result of careful planning. Since Quarians seems as prone to developing romantic feelings as humans, I suppose Quarians would be more prone to platonic romances. Space is limited on the flotilla and it's possible that Quarians are used to retreat to an inner self. A Quarian, even a mature one, might therefore be prone to hide her feelings, rather than act upon them, like Tali does.
... or they could just use those nerve stimulation programs

I don't think sexuality and intimacy is unheard of in Quarian culture, only the physical contact part. I don't think they have too much reason to hide their feelings, but they do still have to put up with the difficulty of actual physical contact (hence my answer to your previous point, about frustration with their suits).
I was also wondering if the thight control of births together with other aspects of Quarian society I mused over above would not lead to a sort of society where marriage would be brokered by families rather than individual choices. This could be a possible problem for Tali/Shepard. Shepard is a Hero, but he is also depriving Tali's family and clan of a baby for future genrations.
Typically arranged marriages are for purposes of distributing wealth or resources, not controlling birth rates.
Quarians already share material wealth anyway, and they already have laws about multiple births. As long as they obey their own laws, there is no need for it. Tali also doesn't mention anything about brokered weddings, which is something I imagine she would have covered in ME1 when talking about the fleet.