Hi Dale,
Sounds like you've found the needed info and got past these issues. Let me know if you are still having troubles.
As for installing in the GAC, you cannot do that unless you have control fo the server, so your only hope is if you can convice Go Daddy to install NeatUpload in the GAC which somehow I doubt they will do.
In short, I think you will have to live with the limitations imposed by Medium Trust. You won't be able to use NeatUpload but uploads should still work. You will likely have issues if you try to run multiple sites they will all use the same theme.skin file from App_Themes/Default. The VirtualPathProvider won't work under medium trust so if you are using the theme.skin file to customize design you will need to use the one in App_Themes/Defaul instead of the one in the skin folder. I recommend sticking with css for design anyway so thats not a huge issue.
Joe