1). I have not tried that, but as far as I know the AD2USB is powered by the alarm panel. I run this with USB over a 100ft Ethernet cable without problems.
2). HG, using this app, create virtual sensor for each alarm sensor so you can use it to drive events. Fore example I use the garage door sensor to switch on the garage lights and I created an additional app that makes HG say things like "Front Door Open" based on the virtual sensors.