Nonliving matter, ultimately.
Why would the progenitors be less complex?
Their complexity wouldn't necessarily be less; it just wouldn't be irreducible.
How old does Behe think the galaxy is?
I'm sure he accepts the consensus figure, which if I recall correctly is 13 billion years---plenty of time for an intelligent race to have evolved elsewhere before there was any life on Earth.
This sounds like a contradiction. Explain how this is possible, if you would - and keep in mind that this progenitor race needs to evolve from non-living matter.