I've always understood pu'jIn to mean "map." Does it also function as "blueprints?"
Yes. I have in my email archives a forwarded fragment of a relevant email from Marc Okrand in November 2009:
I did see him [Maltz] earlier today as he was running off to grab a cup of coffee or something. I told him about the lack of good words relating to architecture. He said he wasn't an architect himself, so he'd have to think about that. But he did know the word for "plan" (the big piece of paper). He said it's pu'jIn -- same as the word for "map."