1. Again, AHP probably CAN be modified to do it, but that would only work if the PC is turned on, and the X10Nets service is running when the power comes back on (if your PC is on a UPS, that has enough run time for that). The CM15A can't do it all by itself, from what I was told by the X10 folks. If your power goes out for a few hours, and your PC shuts down (or the UPS dies), then AHP won't be back up in time to receive the "power is back on" trigger from the CM15A and act on it.
2. I tried again last night. I created a macro "P16 On", to turn on one light in my house. I also created a dummy appliance module, P16. I unplugged the CM15A from the wall, and plugged it back in. Nothing. I did this with the USB cable connected, I didn't try it with the cable disconnected, but that shouldn't make a difference. AHP didn't see the command. I usually find that it only sees the command when the X10nets service starts up, and first connects to the CM15A. I'd have to restart the PC to get that command again, but it does seem to come down the powerline at that point, as my other PC (also with a cm15a attached - for monitoring) sees the command at that time. Since I can't guarantee that my PC will be up and running when power is restored, I will stick to my PowerFlash solution for now. If AHP gets the feature in the future, then I might use both, as the Powerflash won't work for an outage that is less than a few seconds (perhaps there are capacitors in it that need to discharge or something).