Let me wave my magic typeglob and point you at user settings, where there's now a checkbox where you can ask for a private /msg every time someone replies to one of your nodes. Easy, huh? (Been there for ages, and every typeglob is magic. Oh well.)

The second one is possible. I've been toying with the idea of working up an XML-RPC interface to Everything for a while, and it's still in my mind. That's something for pmdev to consider, though. Meanwhile, head over to The Everything Bible, and look for the section on the Public API. There's useful information in there that can help you write a program that'll work right now, not at some point in the future.