1/ It runs off 9v, so that's relatively easy to produce, how long it lasts... that's another story. There are battery pins on the PCB, so it wouldn't be hard to solder a header or if you want to test it quickly, you could solder a 9v battery connector to the points and test it out.
2/ There is a reasonable amount room in the case to fit a few 18650 batteries. You would want 3 of them in series to produce the required voltage. However that's going to produce a bit more than the required current and may well require a small transformer / voltage regulator to bring the voltage down to a nice 9v.
I do recall Jerry saying the device can be powered from a voltage range, but I don't recall where that was posted (or I may well be mixing that up with some weird dream I had).
I do have the intention of trying to power mine from batteries at some stage in the future. Just when, I'm not so sure.