This property is built in the 50s or 60s and the building codes have changed a lot, how to approach county to get this info?

https://finance.yahoo.com/news/does-devon-energy-corporations-nyse-191430577.html

That might help with the areas to look for or avoid.As far as Indy goes, townships and zip codes aren't everything.

Some allow you to change code with app so others cannot re-enter.

Pick one zip code, or one neighborhood and a specific type of property and focus on that for a while. 

I can't recommend any books, but for foreclosures and tax deeds, a good place to start is to get all the info you can from the sheriff or court house clerk who puts on the auction, and read the state's revised code/statutes on the subject.

I am currently finding a property, then staring at various maps and essentially guessing as to where it falls, then researching codes and regulations in that area.

Make then register a phone # and text a confirmation code, get their IP address?

We've removed a lot of K&T over the years due to Insurance mandates & code requirements.

When building a duplex and i'm the GC do I need an engineer to be involved or can I just get by with an Architect stamping off on my plans and making sure they are up to code?