Hi,

I would not worry about the automatic sync. You can set the battery option in OneNote options to consume less power while performing activities (advanced options)
For the second part of your question, this is done via pageversioning. That has some theory behind it. I wrote a blogpost about it and maybe it will give you some insights on how versioning is done in OneNote.
Have a look here: http://wp.me/p57J76-bZ