Bethesda has nothing to do with Nexus. Windows 8 is new, and not everyting is set up to work with it yet. Did NMM ever load to your computer? I had to enable it as administrator in order for it to load, but once it did it worked fine.
What water bug are you talking about?

It took me about half a day to get around it and I got NMM to work. Once it started working, everything went smoothly. I think I posted this too soon, venting my frustration after two hours of hitting blocks in the road. Funnily enough, it was a set of YouTube tutorials that saved the day.

The water bug in question occurs when you have the Dawnguard expansion installed. When you dive underwater, the screen is covered with a single color, usually just green or black, depending on what environment you're in. This is apparently universal, regardless of what OS you're using.

I'm just saddened to learn that Bethesda has walked away from fixing these issues and we have to turn to third party support. My initial caution and fear of the mod community has since subsided, as I've now learned that it is made up of very capable programmers, many of whom used to design games for large companies as well.