The taskforms are *not* gwt but Freemarker templates.
But in short for the last two questions:
BPM Console questions are better asked in the bpm console forum
@Johan: The freemarker templating is still basic (only IO from the user).
If you want to incorporate the taskforms in your own app, the best place to start is the BPMC svn. It lives under 'soag' in the JBoss svn repo.
Widgets/wizards are not supported (yet), but I'll take this input to the BPMC team.