Hi,
1. Ideally, TDS is required only if the consideration for immovable property is 50 lacs or more. Since, in your case consideration for immovable property is less than 50lacs you are not required to deduct TDS. Assuming that amenities are not in the nature of immovable properties.
However, if builder is fine with TDS, you may just deduct the TDS and leave the litigation behind
2. I am not aware of any such defaulter list.