A way to retcon your first argument in is that perhaps the Predators weren't so wrong as Machiko thought in the AVP comic series. Maybe simultaneous convergent evolution did create the aliens. The aliens could be the ultimate cleansor once a population has exceeded its limit, kind of like how the human population is becoming on Earth. Also, I can make the same argument about EU finally being referenced to in the movies. As for the predators, there are differences in genders between the yautja and the hish. It just isn't said whether or not yautja can change sexes as well as the hish.