Miners tend to keep whatever coins they think will increase in value, and sell when they see the coin going sideways or down. Botnet owners have little of no overhead, so they just dump like mad. There is absolutely no positive aspect to having botnets on your coin.
1. I would like to see actual evidence of this as opposed to people just stating it. Is there any?
Theory strongly says that it is irrelevant, given perfect markets (which in the case of Monero actually is true!).
People earn in what they happen to get, and save in what they want. If these two coins do not coincide, they make a conversion between earning and saving.