Ohhhhh ....!!! *That* kind of fertilization! Do you have any reason to think there's pollen around to fertilize open females?
I can't answer the rootbound question. Yes, herms can happen up until harvest, and the later you wait the more likely you are to find them (strain dependent to a great degree).
Fully swinging means fully changing from one sex to another, and in regard to hermaphrodism, there is a spectrum of expression (including in animals and vertebrate life). The 'best case scenario' is when you just get a few late flower bananas, and they really do look like tiny bananas. They occur too late to seed or affect bud production, whereas if you start to get the completely expressed male flower, then female bud production stops. You can pick out the late flower bananas and spritz the plant with water to ensure zero fertilization through this hermaphrodite pollen.
Does that help? I'm still giggling at how I misunderstood you, I apologize.
Oh! How to tell if they're fertilized, usually, since it's this early on, what should still be lots and lots of white pistils popping (this is very much strain dependent, I'm hearing of strains that are finishing under 50 days, that's insane) are instead going red, watch for the calyx it's coming out of to fatten, too.