Hi Brad,
PAL (512 lines) and NTSC (480 lines) are standards for broadcasting and screens were designed to show one or the other (but sometimes both) depending on what country they were sold for use in.
VGA is a graphics standard for 640x480 pixels. It became a generic term for the type of connector and higher res screens can be shown.
I have a TV which can display PAL or NTSC from the TV on scart input, and accept PC input via the VGA connector and this is what I use with my Amiga and Morphos machines. I can't connect the Amiga to the VGA input without a scan doubler and even the official Commodore RGB to VGA adapter doesn't create a signal the TV can use.
TFT stands for Thin Film Transistor and is they type of tech used to create the image, so is a different thing to the inputs.
In summary, you can definitely have a flat screen which will take PAL/NTSC input on one input and VGA on another (as I have). You might still be able to get one that accepts both 15kHz and VGA signals through the same input. These used to be referred to as Multisync monitors in the Amiga mags but in a time of tubes, not flat screens.
