Alex, this one of the best questions I've seen on this forum! It's a great topic, should prove very interesting for you and will help you in your purchases and renovations.
1) To learn about the code, read the code. Read the IRC, International Residential Code, for one and two family buildings. The IBC International Building Code for multi-family and commercial buildings. The Maintenance Code for keeping older, building in shape. Your state might have a state specific version of these codes. A call to a town building department, or an internet search should answer that for you.
2) I have found The Journal of Light Construction to be an excellent source of information. I have a book they published in 1992 that was a collection of some of their most popular articles from the previous few years. It's still on my bookshelf. I still subscribe to their monthly magazine.
3) I have a book called Carpentry and Construction, Third Edition, from 1999 by Mark R. Miller, Rex Miller and Glen E. Baker.
Learn all you can!