Career progression Sergeant, Flight Sergeant, Master Aircrew.
Commission if you want to redo OASC and get selected.
Secondary duties, anything that enhances service life for others or the local community. Basically anything other than your primary work, treasurer, committee member, secretary etc of a club, etc etc.
Dont get too hung up on OASC prep, sounds like you have done a lot anyway, best advice is be yourself and dont try and bullsh*t.