re: Fascinating [Venus definitely merits more study]
I agree that a Venus balloon mission with a "deep sea" grapple/trawl would be a good way to find things about about our sister planet, but I think you need a huge mass to make it work well. I'm prepared to be educated here, though.
As for preserved fossils - well it was a long time back, closer to 3-4 Ga than to 0.5-1 Ga, when fossils are found on Earth.
In any case, the total crustal recycling attested by the crater ages would mean that all pre-existing fossils were swallowed and melted in the ~0.7 Ga planetary "burp".