IIRC, the biggest uncertainty is about the singularity. I don’t know if it’s still true, but my understanding was that the consensus is that it isn’t really a true point of infinitely dense mass. That is how our current models say it must be, but many assumed our current models are incomplete and that more accurate ones will show that it must have some volume. And given the extreme nature of them, any updates to our models might have some significant repercussions in other aspects of them too.

Time is relarive to your frame of reference. You are always the source of your own frame of reference, so you can never feel the effect of time dilation on yourself. At worst, it would look like the universe outside the horizon started to accelerate to unimaginable speeds. But you would never feel trapped in an unending, at worst that is simply what it would look like to us.