As for the specific voltage range not sure, you could email them and ask.
I'm assuming that the double AA batteries are ran in series. So in theory the top voltage range is at least 12v. You could run batteries down till it shuts off and then check each battery with a volt meter, add up all 8 and then that'll tell you around the bottom end of voltage.
As for the mA or amps it pulls you would have to use a multi-meter to try and pull amps from the batteries.