RE: VS Tools addin not loading in the Web Client
The format of the class descriptor is longer than your snip from what you are using, admittedly this might be due to the truncation you have already eluded to. I would expect the same format as the examples in the .config that are deployed with default GP, for example,
type="Microsoft.Dynamics.GP.BusinessIntelligence.BIReportDeploymentDU.BIReportDeploymentDUAddin,Microsoft.Dynamics.GP.BusinessIntelligence.BIReportDeploymentDU,Version=12.0.0.0,Culture=neutral,PublicKeyToken=31bf3856ad364e35"
From the docs: "fully qualified type name> has the following format: "<class name>,<assembly name>[,<version>][,<culture>][,<PublicKeyToken>]"
The instructions you referenced say to put the addin .dll assembly in the main program folder, not the normal subfolder (Addins) normally used for addins. I don't know if this is true as I've not done this myself.
You could also try building a hello world entirely new plug in, just in case there is something about what you have build that is causing it not to load, it might help prove that you can get anything working first.
Apologies if you've tried all this before, as it is just regurgitating the documentation, but hopefully it might make a light bulb go on in your head as to what the issue could be.