Registration of the agreement

Hi All, This is Prasant working in a private firm in Bangalore. In April 2013 I booked a 30"x40" residential land from a ISO certified builder in Bangalore. At the time of booking the sales representative told that they will get it DC converted in 3 - 4 moths from that date and within 3 years they will get the BIAPPA approval. But till now the status of the land is same. Its not even converted to NA. Now the representative is asking us to get registered to a different property as this will take lot of time in the process. But I am really interested in the property which I purchased. So I wanted to some legal documents in order to be safe in future. Right now what I have is the booking reciept from the company and I have an agreement which is not registered. Can anybody please suggest i) if I get the agreement registerd (in a sub registrar office), will I be safe? ii) What is the validity of the registerd agreement? iii) What other options available for me in order to avoid cheat from the developer. Thanks in advance. Regards, Prashant