The LCDs don't necessarily require power switches because they auto-power down & sleep when they don't receive a composite signal (noted in the original post). They work exceptionally well this way when tethered to cameras; when the cameras sleep, so do the displays. There is really no need to wire inline switches.
Many Radio Shacks carry the type L--yes--but most do not sell an L with wire leads (it comes with galvanized pins that require you to buy the companion brick + female part). They only sell their interchange brand, and for a pin adapter, they charge almost $6/pin (I suppose stock varies across their stores, and a site like Mouser likely has the pins if you prefer pins). I solder leads to the board because of this, and it does not impede on the pin adapter from functioning normally. I've also recently been wiring these displays with 2-Wire Keyed Electrical Quick-Disconnectors (viewtopic.php?f=6&t=593
The power adapter specs were disclosed in the original post as noted above. The LCDs will receive a varying degree of amperage. I have tested 2 displays on 1 DC-AC brick up to 3A. 1.5A produces enough power, but it is noticeably dimmer on both displays.