You can send us ftp info and url and admin login to take a look at your install for the thumbnail issue.
As far as your forum block that could be an issue with using such a newer vbulletin released far after vbGallery 2.51 which was released back in 2010.
There literally has been no work done to the 3 branch since before the release of vb4.
The recent build update was merely to include the issues reported recently into the 3 branch since they where already incorporated in vbgallery 3.0 series
I can the thumbnail issue but the code here should be fine unless there are other issues with using this old code on newest PHP's.
The vbgallery 2.x code branch is here mainly for archival and use on older vb3 series which where released when it was current.