Kilo,
Yes, those that joined the old pension scheme will be able to remain on that scheme, and take your pension whenever they leave the RAF. You will also have a 2 year window, from 1 Apr 05, to decide if you wish to join the new pension scheme.
Anyone joining the RAF after 1 Apr 05 will automatically be on the new pension scheme.
C_S
Not really sure about how Officer commissioning terms of Service will work, but I guess that a PC will be 18 years rather than 16, in the same way that a career to 18 years for non-commissioned will entitle them to an EDP (instead of the current 22 years).