I looked at your site your plugins will install correctly if you follow the directions. What I find is something very simple I touched on above.
I looked at your gallery and your xml plugins in the install directory where 644 permissions. The instructions state they should be 777 permissions. All I did was set permissions on the xml files and then under the gallery admin generate the plugin and install it in the
vb. You can do the same for reviewpost classifieds I left those alone so you could do it to learn what you where doing wrong here.
You will also have to remove those static links to any of our products after you install the proper vb4 navigation.
Likewise as well you did not replace your showcomments template either and I replaced that for you.