There are various hypotheses , of course, some of which have significant evidence behind them. But that's what is so magnificent about science. But I don't suppose Dr. Brown would understand that. In any case, this is not an indictment of evolution, nor even of abiogenesis. A theory is not necessarily incorrect because it is incomplete.
Abiogenesis is a separate issue, and a difficult field to study.
It did not. Because we don't look for them there. When you're just looking at a slab of rock, it's hard to tell a meteorite apart from the terrestrial material. This is part of the reason astronomers go to Greenland and Antarctica to find meteorites. It's far easier to recognize a meteorite embedded in ice than a meteorite embedded in rock.