Do you want to spend your life hacking gear or getting the job done?
Get the PCM-M10 and record with built in mics. Shockingly low noise, both the built in mics and recorder. IMO this is the best recorder out there. Battery life, ergonomics and quality are all outstanding.
Standalone recorder with careful positioning (gaffers tape to secure it in your books or bag with mics pointing out, covered with cloth), and the remote control, you can ensure a successful recording result every time.
And after that, you if you want to record other stuff, whether ambient sounds, family events, or music, get some external mics and plug in to the M10.
As for Knowles FG, I have run them off the Sony M10 plug in power. The sound with these little mics is incredible if the volumes are reasonable. But they are easily overloaded. I don't think plug-in-power will hurt the mics, but I can't guarantee it.
As for a battery box, I would try to avoid it. More to carry, and more connections to fail...
Good luck!
Richard