Delay by the builder in offering possession of the flat

I'm planning to file case in State Commission for the delay in possession of flat, my queries are as under : a. If the Buyers' Agreement valid even after the unreasonable delay of more than two years b. If the clause of 'Grace Period of 6 months' mentioned in the agreement on account of delay in getting the Occupation Certificate valid in case the builder has not applied the same even after delay of 2 years or within the completion time frame of 30 months of signing the agreement. c. It's the builder who delayed giving possession of the flat despite taking 90% money in advance, does he still enjoy the right to appoint arbitrator. d. I paid penalty @20% on delayed installments, do I have the right to request the courts to award me the compensation at the similar rate of interest which builder has taken from me....though, it entirely depends upon the court to award the amount. e. The most funny part to ask a lawyer - do I need to hire the services of a lawyer in State CC, particularly when I do not need to quote any laws or judgments in my application and about 5 cases have already been decided in favor of consumers against the very same builder.