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Good question on the window while using the ring switcher. I have the same problem and do not see an obvious answer to it either.
As far as the wall plugin it is not in an official release yet, but is in head for svn. Depending on your distro there may be someone building packages based on the nightly builds but I would use that with caution.
Note: I think, though I am not positive, that the Wall plugin is distinct from the plane plugin. The plane plugin was removed from core because it was rarely used if I recall correctly. The wall plugin uses the same plane concept but is distinct.
notice that it is like the plane plugin but it is a totally new.