The king looks a bit like Pokkle, so I'm going to say he's the most advanced Nen user of the bunch. I don't think teaching is going to happen, but the guards and monsters will be pretty strong anyway when they combine their physical capabilities with nen potential.

As for the one-off genetics, it's hard to say. If we use that current logic, that means that the queen would have continues to eat crabs, turtles, scorpions and cheetahs along with humans. My impression was that ever since she acquired a taste form humans, she's been eating them exclusively.

Thinking about it, there isn't very much "ant" left in them anymore. The funny thing too is that the queen tries to birth a king instead of future queens. So what happens to the next generation?