If you can please add the "exhibit:preview_class=" tag to the list of post config tags (i.e. the post config dropdown).
All of the options that appear in the post config dropdown are listed at the bottom of your exhibit10.cfg file. You can add anything you want there, including the preview_class entry. Just add a line like this to the end (actually anywhere) of the config file:
My Preview Class:preview_class=classname
is there anyway I can disable the dynamic loading of thumbnail when the mouse is hovered over the image icons.
There isn't a config option for this, but...
That should prevent the thumbnails from popping up on mouseover. But man, that's one of my favorite features. ;)
I wish I knew what your watermark issue might be. If I had better access to your server, I might be able to say, but without some hands-on debugging, it's pretty difficult. If you really want to get into it, email me: ringmaster [at] midnightcircus [dot] com
Apart from the above, I've read your suggestions, and I'll see what I can do for the next version.