They truly were and it was a grievous blow when you all disappeared. As for your Vision, yes, he was here for a small while. There was a mishap with someone a demon, and both Strange and I helped strike deal with Mephisto to rid you of the demonic taint that basically helped you procreate? It was a strange circumstance, but they seemed like normal children otherwise.
It supposedly exists. I know not where it would be, but like many relics, it's said to be lost in the crossroad realm of Midgard. Your world does seem to attract a lot of oddities and attention.