The hetaerae could be doing any of the previous or just looking pretty, or having sex for entertainment. They could be dressed or naked. You definitely need to focus on the education of the hetaera. Apparently rhetoric was one of the subjects studied. By bestiality I assume you mean sexual relations with lower animals.
Agricultural cultures involve more bestiality than manufacturing cultures.
But even though the mythology involves bestiality, there is no indication that it was excessive in the society. Just as women having sex with animals is an entertainment for men now, it was, no doubt, an entertainment then. But there is also the problem of monster births. Numerous animal and human babies are born which are monsterous in appearance or construction. Usually these babies are born dead, but the evidence is still there.