The last time I used the tool, I was seeing the same message for the Content entry, though I wasn't sure why, though I suspected something with our proxy configuration scripting. The directory was correct and permissions were good. Everything else came up green for me, with the exception of that. I can say that it never seemed to have a negative effect. Computers still downloaded updates from our downstream WSUS servers. I never ran into an issue with the iuident.cab check though.
WSUS Server Connectivity
content: Error: Forbidden (Incorrect proxy client configuration - use settings tab to test proxy configuration settings; may also be caused by misconfigured SSL implementation or access rights on WSUS server)
This is a unique issue affecting some WSUS servers, because the Diagnostic Tool improperly assumes all HTTP 403 errors are proxy errors. As it happens, if the Directory Browsing module is installed on IIS7.x/IIS8.x, but directory browsing is not permitted on the target (as is the case with the /content v-dir), IIS returns an HTTP 403.14 ... the DiagTool describes that as a proxy issue. It's not. A WSUS server should not have the Directory Browsing module installed. If the machine is a dedicated WSUS server, uninstall the Directory Browsing module, and this message will clear. If the machine has some other app/service/website installed that requires the Directory Browsing module, then this message is unavoidable, and meaningless.
iuident.cab: Error: NotFound (Omitting required port suffix on URL to access WSUS installed to port 8530 or resource is unreachable)
Under normal circumstances, this is a missing file, almost certainly. There should be a copy of iuident.cab in the root folder of the WSUS website and the root folder of the Default Web Site when WSUS v3.2 is installed. The file source is %ProgramFiles%\Update Services\selfupdate. However, WSUS v6 does not use the Default Web Site, and it may be that we're checking the Default Web Site (even if WSUS is installed to port 8530), in which case on WS2012 this would also be a false indication.