I think I already replied about the computer power button, but here goes an answer to your other problem.
I wanted a universal switch to disable all power to my cab like you are talking about, but I also didn't feel like compromising/opening up a power strip.
I went up to fry's and grabbed a cheap 10 foot extension cord.
Grab the heaviest duty switch you can get, think mine was 6amps at 250v toggle switch. It feels really solid.
Cut open the extension cord carefully, making sure not to cut the internal wires, at least not all of them. Cut just one of the wires, doesn't really matter which one.
Solder the ends onto the toggle switch, use lots to make sure you get a good strong connection.
Wrap it up with as much electrical tape as you can find.
Now you have a heavy-duty extension cord with an on/off switch that can be plugged into anything you want, power strip for me.
Some people have used the switch on the power strip, but I found this method easier than cracking one of those open. Good luck with everything.