If your licence was issued in 2007, it will need to be re-issued in 2012. However, it is your SEP Class Rating which needs to be renewed; even after the Rating is renewed, you will still need to apply for licence re-issue in 2012.
There is no minimum hours requirement before taking an SEP Class Rating renewal Licence Skills Test (which is not the same as the original PPL Skills Test - it has less content); you will probably need to do some refresher flying before you fly the LST with an Examiner, but assuming you have a valid medical and pass the LST, the Examiner can sign you up immediately after the flight and that's all there is to it.
There are no exams to take either.