Note that the disk error in Win7 is because of Win8's fast startup (partial shutdown) feature. Go into your Power Options control panel, "Choose what the power buttons do", and turn off fast startup.
As for your other problems, could you please go into more detail? You should just be able to add the additional copies of Windows to the BCD menu and call it a day.
Team Anandtech: Assimilating a computer near you!
GameStop - An upscale specialized pawnshop that happens to sell new games on the side
Todd the Wraith: On Fruit Bowls - I hope they prove [to be] as delicious as the farmers who grew them