Ippc

I have passed cpt with 100 marks.I frankly say I didnt made any efforts to clear cpt ,just bcoz of my 12th knowledge,I did it.But now I have decided to work harder for upcoming levels.I want suggestion if i should opt for single group or both.Please smone tell me the last date for registration for May 2015 test for ippc.I also want to know the difference between "with articles " and "without articles".Which one is suitable for me ?