Purchase of agriculture land - Seller delaying the registration

I have purchased 4 acres of agriculture land in Krishna district and made the agreement in Nov 2013. I have paid 70% of the property value in cash during the agreement. The agreement states that I will pay remaining 30% 20-Feb-2014 and will register the property in my name. The seller kept postponing the registration till now showing various reasons. The new government being formed in AP announced that they will waive off all the farm loans. The seller is now showing this reason saying he will wait till the loan waiver is implemented and saying that he can write a handover agreement if needed. We are worried now as the cost of land is appreciating in the region as there is hype that the new capital will be formed in our district. 1. Is it safe to get the handover agreement 2. Can I pay any further amount like 20% more and document the total in the agreement 3. In case I pay in cash what would be the proof of payment 4. Can the seller any time in the future tell that he is not willing (or having problems) to sell the property and say that he will refund our initial payments. If yes, what should I add in the agreement to have legal support that the land need to be registered on my name in any case Your help is much appreciated. Thank you - Krishna