I'm building an XBOX 360 Laptop too at the moment, I'm no expert but I'll try and answer some questions:
2. I've heard that the hdmi port is very difficult to desolder, so I would use VGA (pinouts available on this forum)
3. With my laptop, I'm running everything off the screen's power supply, I'm soldering two wires from this to the xbox power brick.
4. If your buying a monitor and disassembling it, then use the video card inside the monitor
5. I can make custom cases for anyone, I have access to many CNC machines for free including: Laser cutters (can engrave too!), 2x 3D printers, CNC routers, millers, lathes etc . Ideally I would want/ask you to design the case on a 3D modelling software, however I would be able to do this for you if that isn't possible, obviously at an increased cost to you. Alternatively if want you want I already have a design for, then there would be no design cost. The cases will look awesome as everything would be computer controlled
Having not made cases for anyone before, I'm not entirely sure what to charge. It would of course be the cost of the materials, use of machines (which should be free) and what I consider to be reasonable for the use of my time (It won't be too expensive, I believe that we can all help each other out on this forum!)
If anyone is interested, contact me at: email@example.com
I'm near to creating my case so will post some pictures in the next month.