Hobe,
Two of the best investments I have ever made in regard to "the unwritten stuff" was acquiring copies of "The Rules of Professional Baseball", written by Chris Jaksa and Rick Roder (aka J/R):
http://www.rulesofbaseball.com/
and "Baseball Rule Differences" (aka BRD), written by Carl Childress:
http://shop.officiating.com/x/product/brd2006
The vast majority (though not necessarily ALL) of the unwritten stuff can be found in these two books.
In regard to your statement regarding balk calls not being "questionable", I say Balderdash!!! If the umpire misapplies the rules in calling a balk, it is both appealable and protestable. If he errs in judgement, it is neither. If the umpire doesn't want to hear about it, that's his prerogative. As the manager, your prerogative is to say, "I protest"; then return to your dugout.
JM