Comments and idea-spinning...
As pointed out, it's been explicit for a while that--at least in some circles--it's not safe, let alone a wise career move, for a Caldari to be known to be gay. I'm not sure whether I'd expect the resurgent patriotism at the moment to make this more or less the case: I'd expect "traditional Caldari values" to be big, but that those values would be re-cast in ways that suited the current leadership. That depends a lot on gender roles, though, and since Caldari seemed to be originally intended as a non-gendered society I wouldn't expect the sorts of military/paramilitary brother-bonds + breeding programmes that you might see otherwise.
Gallente (but not necessarily other Federalists) generally don't care who or what or how many you have sex with. I'd assume a low-ish, Euro-style age of consent. I'd also assume it'd be a big deal to establish consent, since rape would be seen as a crime against individual sovereignty. You can do pretty much whatever you choose with your own individual sovereignty, but having someone else take that choice away is fundamentally badwrong.
I'm actually a bit surprised at what's felt like fairly vanilla (serial-monogamous?) nuclear family relationships when we've met Gallente. I haven't read everything (yet), though. Gallente customs concerning childcare and child education seem to be important and not currently well described.
I've long seen Amarrians as holding that heterosexual marriage is for duty, and if there's affection there as well that's a nice extra blessing from God. I've never been clear about the official and actual Amarrian views about sex that doesn't happen within marriage; about contraception and abortion, which affect things a lot; and about the effect of relative status when choosing acceptable sexual partners. My own assumptions are based on Roman models, complete with the infamous
Mercedes simile. I could be quite wrong.
I'm too close to Matari views of appropriate and inappropriate and pragmatic expressions of sexuality to talk about that fluently without a long run up and maybe some alcohol. "It varies."
I was involved in an IC discussion recently where a non-Matari reproached a group of Matari for being intolerant. I was trying not to pour accelerant on the flames at the time, so held my tongue, but in my experience tolerance is a Gallente virtue, not a Matari one. There's quite a bit about people's lives that Matari don't much care about (especially if whatever it is seems to work for that person's particular clan), but I don't think Matari make a virtue of putting up with differences in the things they do care about. I think this can be a bit challenging for some players, both those from outside expecting that the "free the slaves" people will be all huggy and understanding, and those from inside whose clans might have quite different and incompatible ideas about what's acceptable behaviour.