Hidemyass logs everything and gives the logs to law enforcement at the drop of a dime, don't you remember that lulzsec dude who got busted using them? If you use VPN to Tor, you exit from the VPN to the Tor entry guard. I am not sure how to explain it. The VPN software routes your outgoing traffic through the VPN servers, your outgoing traffic initiates a Tor circuit from an entry guard, so the last VPN node connects to the entry guard and then the Tor circuit extends from there.