though this sounds very cool and but all too promising to complete.
I doubt you will be able to make the optical drive thinner, even the newest xbox 360 slim optical drive are just a fraction of a size smaller than the the phat xbox 360 optical drive. You might have to RDC or you can cut the back panel and work that around the optical drive. Hay why not run it externally?
Just need to extend the power cable and get a longer sata cable.
When talking about the touch button you mean on the xbox 360 slim??? Not the same PCB interface as the phat, a simple tact switch will not work. If I were you I would use the phat instead since the interface has a simple SMT tact switch. Can easily be desolder and a wire can be run to the front of the Acer panel. From the looks of the Acer anyways it has a tact switch. maybe you can tap into that and to the from interface PCB on the phat xbox 360??
For the DVI you could just get
Dvi to HDMI adapter or
Dvi to RCA and make your work load very simple.
But if you want to put in the extra effort here I can help avoid with the pulling of the hair lol some pinout for the DVI interface.
Btw reading about the Hdd being solder to the motherboard.. Wow that kind of sucks... But don't worry I found something you are going to like
This Hard drive caddy adapter for thin slotted optical driveJust have to pull the Hdd out and take it out of the holder and slide it into the slim slot adapter and i guess done
Actually there is a lot of little things you are going to have to think about. Though this Idea is wonderful and if you can pull it off amazing job.
I think its ambitious but hay ambitious built rome. So good luck