Do pdf’s just become extensions of your website? I seen google being able to crawl through them, so they do they work like that or no?
also yay for me getting on bing’s first page results for “point of sale chicago” 
Not really - if you do a search for “Forty eight million US dollars is withdrawn from my accounts in fifteen minutes” you will find a link to an ebook I wrote which has been online for nearly a year. There are quite a few others in ebook directories. the PDF has never been indexed! If it were a webpage it would be indexed in days.
Yes, Google will try to crawl all major file types it finds on your website, including PDF and MS Office. How successful it is at crawling them will depend on how well set up and accessible they are - if you tag them, this should help Google determine the structure and context of the document, which will improve the search performance.
Google indexes PDFs and all sorts of documents (word documents, excel spreadsheets, powerpont presentations etc) no problem. The only thing you are missing from an indexed PDF is the markup you can create using HTML, like <h1>s I think.