So you applied the updates to all components? So are posts still disappearing? There wont be anything we can really do about the two that seem to be lost but the version clash you had could explain those depending on the post conent.
As to Login issues then it is not so much that SP doesn’t handle it but we really do not get involved in it either. When a forum view is requested one of the first things we find out from the WordPress core is whether the user is logged in or not and then the forum responds accordingly by fetching and displaying the appropriate data. I do not recall if you were using some sort of membership plugin but if you are then I would suggest you need to ask this question of their support. If not then whatever is displaying the login form on other, non-forum pages is perhaps not making the correct status checks with WP.