A: You're looking at it. The most up-to-date copy can be found within the GnuCash Wiki.
A: Yes. Go to http://lists.gnucash.org/mailman/listinfo/gnucash-user and http://lists.gnucash.org/mailman/listinfo/gnucash-devel to subscibe.
A: Yes, you can search the mail list archives at http://news.gmane.org/gmane.comp.gnome.apps.gnucash.devel and http://news.gmane.org/gmane.comp.gnome.apps.gnucash.user (and http://news.gmane.org/gmane.comp.gnome.apps.gnucash.german if you speak German).
A: Yes. Many of the developers hang out on icq in the #gnucash discussion on irc.gnome.org. Also, there is a wiki online at http://wiki.gnucash.org/wiki/GnuCash.