MadCow

I have a flip out standalone monitor that I am going to add to go with my Alpine headunit and either a car computer or a standalone DVD player. My questions is wiring mostly. For the Screen I need a constant for the clock, and then I need a power source that is tied into the ignition. First can I hook the constant to the same wire that is being used for the constant to the Alpine deck. Second, where should I get my power source from for when the car is on, or in accessories?. Lastly I plan to put the DVD or carputer in the trunk, with a distro block could I get my power from my amp kit and use the Remote amp wire as the power on switch for the device?