If I wanted to build an 80% lower what paperwork and other hoops have to be jumped through to be legal. I have seen alot of other info on the topic but hadn't heard about this.

For the Feds, zip, as long as you don't build an "assault rifle" and you don't build it "with the intent to sell".  In NJ, I couldn't find anything in the laws about building one for your own use, except a little section on 'zip guns".  Take a look at your state's website, see if there's a link to the laws & do a search.

I think all the states use a format like NJ does,

http://www.state.nj.us/

HTH,
Norm

OK so it goes like this, if I buy an 80% lower and finish it myself. Then I buy a post ban parts kit, the gun doesn't need any type of federal paperwork. No background check, or anything. WOW, I just figured that the govt would wan't to charge a fee or something. Very Cool, I like it.