You can buy TFT LCD touchscreens in almost any size. Just depends on what how much money you want to shell out.
For multiple monitors you can get a VGA Splitter. However you will be tied to go with whatever the maximum resolution is on your smallest monitor. If you use an NTSC/PAL screen you will be tied to 640x480. I would reccomend going ALL VGA screens.
Also these things have been talked about recently so please in the future use the search first 8 )