Make sure you are logged in to Windows as an Administrator and make sure your system clock is accurate both time and date and time-zone.
Also make sure that Windows is up to date, especially Internet Explorer as the interface depends on it being up to date and at default levels.
Those updates that wont install I can't help you with but they may be able to help here: Windows 8 Forums or don't forget that Microsoft always offers free help for update problems.
When you ran MVT I assume you downloaded it from https://mvt.mcafee.com ? Try uninstalling it and reinstalling then running it.
Thanks for the ideas. Spent several weeks intermittently and unsuccessfully trying to resolve issues preventing installation of Win8 updates. Whenever I did have some limited success after extensive digging for solutions, I went back to retry MVT but still couldn't make it work. I finally gave up and upgraded to Win10 (which was free and relatively painless). After a few weeks of stabilizing Win10, then uninstalling and reinstalling McAfee Internet Security, I now have a working anti-virus tool where I can reset the update preferences just like it says in the shiny brochure. Whoopee!!
Glad things are OK now ;-)