The RCA ones can only have a max of what RCA supports (O-o 320x240 I think?) and normally they are actually half the size.
While the Mimo Monitors (displaylink monitor), are cool, and usb powered, they don't work standalone. They need another monitor hooked up to initialize the GPU. I have one of the first Mimo Monitors. I was going to use it for a double din all in one computer, but like I said, I'd have to have a second actual monitor hooked up for it to recognize right and piggyback onto the GPU.
This said though, these will be running linux, and as such, DisplayLink has an open source linux driver for it. Maybe it can be rewrote to work without a second screen then. If so, that'd be useful.
On a side note, I also have a resistive touch screen I added on top of my mimo monitor. This could probably be used for touch screen input like asked about above. It adds another USB device though, and Mimo Monitors generally need two usb ports to begin with (one for data and power, a second for extra amperage in the power)
Hope this shines some light on some things before you go buying stuff. I'd write/rewrite the drivers to work, but I have no clue about that stuff. (I program VB, C#, and Web languages, so nothing low level enough to work with drivers)