Ok, so here's the overall situation

  1. Fresh Windows 10 Install
  2. Installed IIS attempting to include .net 3.5 in this install - it failed pulling the package from Windows Update due to my WSUS server.
    1_ Skipped the .net 3.5 and installed everything. IIS, .net 4.5, Hyper-V etc.
  3. After fixing my Group Policy to pull from Windows Update I attempted to install .net 3.5 at which point I started getting a 0x800F081F during the install(among others).

The fix. Uninstall IIS. Restart. Install ONLY 3.5 and no other components. Then re-install IIS.

Here's the question on Microsoft's answer site that describes my problem and everything I tried. http://answers.microsoft.com/en-us/insider/forum/insider_wintp-insider_install/how-to-instal-net-framework-35-on-windows-10/450b3ba6-4d19-45ae-840e-78519f36d7a4