Lawyers suggestion key points:

1. Buyers association either registered or unregistered can represent the case. However, registration would give more benefits so  the builder is forced to talk to one identify who represents buyers benefit. Builder will naturally respond / negotiate once an association is formed.
2. Registration can be done before Occupancy Certificate (OC)  but need to get the sale deed clearly checked line by line, by lawyer on this channel showed his suspicion of only 2 blocks ready out of 8 blocks: chances of many issues. Registration agreement needs clear scanning by lawyer to avoid future mistakes as the project isn’t complete.Buyer can register the property but do not tie registration to OC as that will clear all the uncertainty of owning the flat.
3. Possession without OC is at builders cost. Builder is liable to bear all cost such as taxes, power, maintenance etc. Buyer can take possession if builder is giving alternate power but should be at his cost not owners.
4. Maintenance agreement: There is no legal binding to sign any maintenance agreement during registration you can deny as it is one sided. Strictly No to maintenance agreement of 10 yrs..Builder cannot enforce this for signing. Demanding 1 year maintenance cost in advance is ok. Maintenance payments to be in the name of different or specific bank account. Need not pay more than 1 year.
5. Arbitration clause is not applicable for filing case in consumer court. There is only consumer court for this issue and can be through association and effective through association rather individual. Interim relief for completion of amenities/services can be claimed at consumer forum.