i'm a newbie to these embedded development boards and had initial success with a beagle bone black, i got the combo :
- beagle bone black
https://beagleboard.org/black- and the 7" lcd touchscreen cape from 4d systems
http://www.4dsystems.com.au/product/4DCAPE_70T/ this is a great/awesome combo as it makes the BBB a complete (linux) computer with its own (resistive) touch screen LCD running off a 5 volt power supply ! (not a simple usb port though)
unfortunately linux is very keyboard based & i installed florence (on-screen virtual keyboard) from
https://packages.debian.org/jessie/florence(florence do have various dependencies which needs to be installed together and in addition install the package "at-spi2-core" as a dependency as otherwise florence fails/aborts with errors at every key click)
a screen print:
running chrome(ium) is very heavy on this tiny little board but it works for what's worth!
this still leaves room to patch circuits at the extension headers (gpios / analog inputs, etc)
would likely try the android install as it'd seem android is more appropriate / usable for a touch screen device