Gjs DBus bindings questions (introspection, method names and callbacks)

[Jason Heeris <jason heeris gmail com>]

I'm trying to figure out how to use DBus from my Gnome Shell
extension. I have the option of using the GLib DBus interface, but
then I saw that there's actual Gjs DBus bindings! The Gnome Live Gjs
page only has a link to here:

http://erick2red.github.com/blog/2011/05/28/dbus-in-gjs-and-gnome-shell/

...but I still have a few questions:

1. That page doesn't mention introspection - is it supported? Can I
get away with not explicitly specifying the signatures on the
interfaces I want to use?

2. The method called Notify in the interface definition becomes
NotifyRemote when it's called. Why is that?

3. How do the callbacks work - is it a single function with two
parameters: 'result' and 'error'? Can I instead use two separate
callbacks? Is 'result' undefined if there's an error, or is it
something else (ie. how do I test for success)?

4. Can I make blocking calls instead?

5. Can I connect to signals?

Cheers,
Jason