I have the same problems.
I have a macbook pro mid-2012 with Nvida graphics option.
On mine, I wasn't able to download bootcamp 6 as I don't even have OSX on my machine at all, so I had to use an older version of bootcamp driver support initially. I was hoping the most drivers would work, at least for network cards so I could update them to the latest versions via windows update.
The bootcamp driver support would crash the video upon installing the Nvida drivers as this was the first or second thing it does. I was running into the screen blacking out issue you had mentioned. Booting into safe mode (SHIFT+F8 worked for me) yielded no results in repairing. I ended up having to re-install windows several times. I created restore points before making any major driver change and that has been working to go back after I crash something.
I hooked up the computer via hardwire to the internet, and windows update seemed to update my Nvidia graphics card properly so my started working for the most part.
To install the rest of the software (mainly the bootcamp assistant software, since it won't let you install as "stand alone"....), I had to manipulate the bootcamp installaton source folder. I had to remove any program the computer was hanging up on/rebooting/locking up.
I removed the intel graphics card files, the Nvidia files, mainly.
This allowed me to fully install the bootcamp assistant software. Upon running apple software update, it was then finally updated to bootcamp 6! That really didn't fix anything though.
After all of that, I still have no audio. I believe the audio is related to the intel graphics somehow. It seems whenever I try to update that driver (which is disabled?) it looks like it is trying to install something audio related. The computer just starts bootlooping after this though no matter what I do. I even downloaded the driver update software directly from Intel and tried.
I figured I could at least use the computer without audio, but then I found out whenever the screen blanks/sleep mode, upon waking the computer I get the zig zag too and the computer has to be force restarted!
I can't believe how bad the driver support is for Windows on this machine. I had to jump through similar hoops of fire for Windows 8.1 as well regarding video driver installation. It has always been a struggle trying to run Windows on this Mac, I will never do it again.
If anybody on here has a work around to make this work, please let me know. I have spent about 10 hours so far trying to make this computer work with Windows 10 now.