Is the individual level still relevant to the societal level, so that opposition to race mixing is much more widespread than many have assumed?
Does jealousy still operate on a collective/societal level because nobody wants their genetic pool to be diluted, and many believe that it's far better to take extra precautionary measures than to be sorry?
Are people more likely to be jealous of perceived "outsiders" whose reproductive success is likely to "taint" the genetic pool (presupposing that there would be any change at all)?
We are starting to combine biology with culture... But it is still to the topic so I'll answer. Yes to all, unfortunaltely...
First we need to understand that society is a group of individuals sharing values, traditions and language, history and other stuff for generations. So what goes on personal level goes for society too. (however it has nothing to do with races, rather with cultures and societies)
To your second question, damn yeah. I'll speak about Europe mainly because I know Europe the best in this matter. In male dominated society women become second grade citizens, having way more restrictions than men (like purity culture) and are way worse punished than men. (when the lovers in history here made love and were caught, man was send to slave work for few months, woman was murdered)
For the pracautions, there were many. For women of high standing neutered men were used to guard them from other men, but their genitals were removed to prevent the obvious. Another well known measure were metalic underwear, that allowed WC needs but prevented lovemaking. Also I know that in Africa were measures like sewing womans genitals. Also cutting external parts of womans genitals off. This especially made lovemaking painful for a woman for the rest of her life, well rpeventing sex and masturbation, but also causing health and mental issues because of unfulfilled body need. Needless to say that religious reasons were made up too. That is why catholic church invented the theology that original sin came from woman (not from the devil) and therefore all women are damed to go to hell unless they are loyla to the man they marry and have babies. That is the only way they can save themselves.
Or among Arabs women are kept locked at home and must go out only guarded with male family members or other woman, again to prevent that only think, that she cannot have baby with someone she is not allowed to by men. Isolation then degenerates her brain so then the Muslims have int heir holy book mention that woman is only half human, how coulsd she be fully developed when she was isolated fromt he world, enied possibility to develop into full human being? But it prevents her from being able to survive alone, so she cannot run and since she is contantly guarded, outside man hopefuly cannot get to her and impregnate her.
So yeah, a lot of measures, stronger or weaker were and are still used to dominate women by men who want to ensure that they will have only their babies. In the end all these religious traditions, society traditions, purity cultures... all serve this one thing - evolutionary desire to breed and ensure survival of mens offspring. Nothing spiritual about it what so ever. No god ever ordered that. It came out of animal nature of humans, even if we do not realise it.
And about guys from outside of the group? Well, guy that is unusual or rare tends to be atractive to women, especialy if it is some sort of "bad boy." The reason being that such guy who can survive in harsher conditions tends to be stronger and therefore real competition to men who need group to be able to make a stand...
I'll add another irony. Man has it easier to spread his genes and are also tempted by women, but also they are far less punished by love making to more women. That is why in these "putiry obsessed cultures" we have whore-houses. Men are never much blamed for visiting them, but those women themselves, who get the bad luck of being there are the lowest cast of society. Defintiely that was true at middleages Europe. Even churches were way more willing to help beggars with black death than prostitutes. Churches willing to help these women,w ho weren't married and payed for food with their body, were often refused help by nuns, or any clergy in fact.
That should answer your questions.