http://www.familyhandyman.com/walls/drilling-holes-notching-and-boring-holes-in-wood-studs/view-all
I recently subscribed to Family Handyman. There’s an endless supply of useful things to do and build in there. Ran across this page on their site while I was searching for information on drilling and/or notching studs in prebuilt walls. While it didn’t dig into finished walls, the reference for code/recommendations on the allowed size of bores and notches is great.
http://www.home4c.com/conduit.htm
This reference to sizing for plastic conduit bushings and EMT size is handy in combination with the above. Didn’t realize that neither dimension of EMT actually corresponded to its true size.
I also ran across that link to a list of “Electricians’ Tricks of the Trade” that has some helpful ideas for a lot of handywork and cabling projects.