If my memory serves me (back for vacation...), the Quality Packs (GOLDPK11i...) are periodic 6monthly updates so the latest would be Jun 2012. They are not required but highly recommended ( or understand required when you are doing a fresh new install! ).
the quality pack includes 2 patch bundles, one for the system itself ( network and graphic etc drivers + core OS ) and one for the HPUX applications ( compilers etc...)
There is always a ( or more) README file(s) that you are to read first and full installation instructions.
To download you need a support contract - If you have one, you have all the information where/how to download