1. Well,forming of society or handing over the management of society would purely be guided by the terms of the agreement.
2.it appears that sale deed of the respective flats have already been made.if not,then you have option of recovering it at the time of execution and registration of the sale deed.
3.It is not clear as to under what heads the arrears are falling due. If it is towards the value of the flat then you can claim it as advised above.
4. if it is towards maintenance charge then filing of civil suit is an option.
5. However delay in handing over the society is not advisable as the flat owners will be open to file case in the consumer forum for your deficiency of service.