Hi, welcome to the party!
As stated, it is the Hobbit rulebook that contains the newest rules, but there is also the desolation of Smaug sourcebook (still on the games workshop web store) and the battle of the five armies sourcebook, which can be downloaded for free here:
http://www.games-workshop.com/en-NO/The ... id=1773174The two sourcebooks mentioned above contains the rules for the Hobbit models not covered in the big Hobbit rulebook. The five sourcebooks you have acquired are all in use, bringing the total to seven sourcebooks and one rulebook.
As far as rules go, you should also download the faq's and errata's, which can be found here (scroll down):
http://www.blacklibrary.com/faqs-and-errata.htmlI would also recommend you to go to the Great British Hobbit League's Facebook page. They have their own faq which covers problems not covered by GW.
This should provide you with all you need.
The older sourcebooks are outdated rules wise, but many of them have very good hobby content!
I hope this helps!