The most basic reason, and the one Velikovskians cannot explain away is that if Venus was gallivanting around the solar system in historic times, as you seem to think possible, there is NO way it would have settled into an almost circular orbit, the most circular and least eccentric in the solar system, in the time frame allowed, without having also disturbed the orbits of Earth and Mars, and the moon's orbit around earth. It's just not possible
The 6-minute slowing of Venus's rotation that was revealed by the ESA's Venus Express probe demonstrates that forces we have not yet accounted for are acting on Venus. We see a remnant ion tail issuing from Venus whose original size and potential drag-effect we can't quantify. So blanket statements about what might or might not be possible are, at best, speculative. We know with certainty that the orbits of some comets have circularized, and within timeframes that are not certain.
The apparent rotational resonance of Venus and the Earth, along with the behavior of the remnant ion tail, could theoretically have resulted from a close approach of the two bodies. Since we have no direct knowledge of how close that approach might have been, we're not really in a position to make declarations about what the results should have been. We do know that the moon's orbit does not appear to have been disrupted, so that places the question into a contextual framework.
Cal-Tech studies show that an impact by a planet-sized body can reasonably explain both the damage and orbital situation we find Mars in.
So yes, there are perspectives from which each of the points you list could have happened.
Edited 1 time(s). Last edit at 01-Nov-15 02:03 by Laird Scranton.