Aircraft with unbalanced control surfaces (i.e. if you loose some of them), tend to oscillate between the extremes (speed and attitude). So they go nose up, speed decrease, stall, nose down, speed increase, overspeed. And so on. Until it hits the surface. How it hit we still don't know. But obviously just in a straight level, which is pure randomly, it could also have impacted nose down. It all depens in which phase of the oscillation it was.
Concerning the VS I don't know what you're refering to.
As I (and others) stated long time ago: The ACARS messages don't deliver the cause of the accident, but the outcome. As soon as the aircraft spirals down, you get these weird messages. So it's very well possible that they were created after the aircraft became uncontrollable.
Dani