Welcome back to the hobby!
First of, AUJ - An unexpected journey DoS - Desolation of Smaug
The main rulebook is the big Hobbit rulebook (AUJ). The smaller paperback version from the "Escape from Goblin Town" boxed set includes all the rules, but (if memory serves me correct) only includes the profiles for Thorin's company, along with the profiles for heroes and warriors from Goblin Town. The big rulebook also contains the profiles for Azog's hunters, Rivendell knights, warriors of Erebor etc. There is also a sourcebook for DoS with the rules for Mirkwood rangers, Tauriel and so on, and a "sourcebook" for BotFA (Battle of the five armies). The BotFA one can be downloaded for free from GW:
http://www.games-workshop.com/en-NO/The ... e-Game-PDFProfiles for the models in the LOTR range are covered in five sourcebooks, but only two are still available from GW (namely "Mordor" and "Moria and Angmar"). "Free peoples", "Fallen realms" and "Kingdoms of Men" are all out of print. I am afraid you will need all of them if you want all the profiles.
I hope this helps!