I hate to break it to you, but Venus' crater pattern is dodgy for a reason. The surface of
Venus is very hot (approximately 470ºC) -- so hot, in fact, that parts of it are
molten. Now, you'd be
hard pressed to find a crater on a molten surface, but it is possible -- we've seen them on Venus. Venus' surface has one
interesting quirk, though, which accounts for the
aforementioned lack of craters.
Every so often (I think it's
100,000,000 years or so, but I'm not sure.
Ask a professional.), Venus' surface
wipes itself clean. Craters? Gone.
Islets of molten rock that managed to cool enough to
solidify on the surface?
Gone.
No one I've asked has been able to tell me why this happens (hypothetical answers I've been given have had to do with the pressure on Venus, subterranean floes, etc. Use your imagination), but apparently it does.
Update: no comply says check out my WU in the venus node, the wipe out you talk of is, as i know it, a result of intense tectonics which allow the molten interior to esacpe through fissures
There you have it.
As for Venus' retrograde motion: Again, no one can be positively sure why, but the "accepted" hypothesis is that something big -- very big -- hit Venus early on in its life, thus causing it to rotate backwards. This makes sense, as well, because even if something catastrophic had happened to Venus billions of years ago, it's had time to right itself. So there. QED, I think.