Answering some of my own questions (and some further constructive criticism).
- Possible for males to be born? Yes. It's just that you must use a male of the desired species to do that breeding. While I can see why things are implemented this way (it's probably the most simple way), it feels a bit weird in contrast to any assumptions one might have coming from reality. In game for example CatBoy + DogGirl can only ever yield a CatBoy or a DogGirl. Why not the other specifies-gender combinations of DogBoy or CatGirl? Where this tripped me up was MainCharacter + CatGirl only yields CatGirls, but then I tried CatBoy + CatGirl and happened to get only CatGirls the first few times - so based on the evidence that far - breeding only yields girls.
I think it would be nice if there was like a "Beginners Guide to Breeding" book in the house or maybe an extra dialog option from Talia once males start showing up to just explain how it works.
- I found the Rika stuff, but triggering the shower scene to kick it off seems entirely random chance. And since it's in the house where you don't need to visit if you just use the time skip button, a player could spend hours doing the breeding stuff and never stumble into it. Seems like one would want to make the content a bit more discoverable.
- I still have a couple scenes in the gallery that I never unlocked. Breeder rank A and much time spent clicking through all the locations in the game. With the game giving no hints as to what characters they're with or what locations I need to go so, at this point it has simply exhausted my motivation to find them. That's presumably not what you want the game to feel like.