[USER=313]@jottwehh[/USER]! You're a huge help!
I have been mixing people's builds up, and I'm sorry about that. So many people have been chiming in and referencing each other's builds and it's awesome and helpful and a lot to digest! 
For the record, I'm like 90% sure you can power your computer with a battery, though I'm not sure Windows would recognize you're on a battery like it tends to do with laptops. Also, with our 'desktop' grade components our power draw is probably much higher than your typical laptop so I wouldn't expect much battery life!
Your post was really insightful and your GPU mod (and cutting fan holes) definitely looks like something I'm capable of. The one thing that confuses me about your diagram (the one where you tried to mark out 'zones' for components) is near the GPU. There's the box that says "Up to 195mm." What's that about? Is that your measurement of the largest video card that would fit at all? Or is that the longest video card that you could fit that would allow you to route your cables?
What a cool power adapter mod!
You're right, I am a bit confused about power supplies/bricks. I understand that you need either one unit that does everything (like in a desktop), or you need to make sure you have one unit that turns wall power (AC) into power components can use (DC) and then something to distribute that DC power to your parts.
The HDPLEX 160W AC-DC w/PFC (nanoATX Series) you linked to is what I was thinking of, I don't see how I could fit it (and a powerful enough DC-DC board) in a MC600, but I'd be really excited if I could find a way.
