GameShell powered arcade machine

My next project will be a full size arcade cabinet which is powered by a handheld device. The basic idea is that I can game on the arcade at home, and then ‘un-dock’ the handheld to bring along. The GameShell (mHDMI, 3,5 and WiFi) seems like a potential option as long as arcade controller inputs can be wired in. Guess I could go with bluetooth, but don’t fully trust it.

  1. Will controller input be possible through the USB port exposed externally or would I need to break out another USB somehow? If so, how? (Or perhaps it’s not possible at all and I’ll buy/build another device.)
  2. Does the current version of the OS have support for multiple controllers?

I’m fairly Linux literate and handy with soldering and hardware modding, but also have a busy enough life to prefer a solution which does not require an enormous amount of hacking.