Thanks.
Issue 2 seems to be due to FormIt not being installed. I managed to create a post after installing that.
Issue 1 is a bit different. Basically we've been recommending using the so-called SSO mode and creating the individual resources, linking them with the settings, etc. While that works, it does mean you need to set up the full registration/login/update profile pages.......... but if you don't set the system settings to point to resources, it uses Discuss controllers, wrapped in the wrapper tpl, keeping it all in the same style.
Thinking about that does make the extra steps needed to set up the additional resources, well, redundant. Frankly I've been so focused on the MODX forums (which re-use the main MODX.com authentication and updating etc) that it never really stood out to me that it's essentially double work and cluttering the site tree, too.
Maybe this needs some more thought and community suggestions (what do you think Paul?), and then we can update the documentation to recommend the best method - either keeping it all in Discuss, or using separate resources for login, register and update profile actions.