Joint complaint filed in consumer court

We are a group of persons who have purchased flat in residential project. The possession has not been given to us so we want to file a joint complaint for delay in possession in State Forum. Can anyone answer following queries? Q1. Shall we first file complaint in District Forum or shall we directly approach State Forum? Q2. The property is in ghaziabad, the Opposite Party (developer) has registered address in Delhi and most of the buyers are from Delhi. Can we file complaint in Delhi State COmmission? Q3. Is it compulsary that we register ourselves as an association? Q4. What all documents need to be signed by all of us? Is it enough if all of the buyers sign a POA and authorise one of our representative to follow-up the case? Kindly reply. Sakshi Tuteja