Look at the last pictures. You are just replacing the ribbon cable with the output from the board. RGB/sync and all that are clearly labled. I haven't done this yet, but it looks fairly straight forward. This is the only DIY I have seen for this so far, so if someone has a more complete one, post a link.
I don't remember the brand that I have but it already has the input for A/V cables. Of couse you still need the PSone if you want to give any power to your screen.
No, the way this is done you do not need your PS to power it. You wire up the 12 volt from your psu. Look at how it's done. Fairly simple. I think I might buy one tomorrow to make a portable game rig.
edit:
Also, the smaller wires go to the controls by the front of the screen. That is covered in the initial pictures.