What to write on agreement to buy a car which has loan on it?

Current situation- I wants to buy a car which a pending loan of rs 250000. The seller has fixed the deal for a total of Rs 400000. Proposed condition- I (buyer) will pay him advance of Rs 250000 to close the loan and get NOC. At the time of agreement signing, I will transfer Rs 250000 to seller and get possession of the vehicle along with both the keys and all necessary documents. Future promises- within one or two weeks seller will get NOC from bank and then process of rc transfer will be initiated. As the seller initiates the process of RC transfer and both the parties(buyer and seller) stamped their sign on transfer paper I will transfer rest of the money (Rs 150000) to the seller. Requirements to be mentioned in agreement - 1.total liability and responsibility related to vehicle (including any pending challan, any kind of loan, any civil case, any accident case or any incident case) that has has happened before handing over the vehicle to buyer (i.e. date of agreement) lies with the seller and after that all these conditions lies with the buyer. 2.if seller fails to provide NOC from bank tothe buyer and breaks the deal for selling the car to buyer, seller will be held responsible and he will pay the buyer same amount transferred to him(seller) as mentioned in agreement for closure of loan with interest. Now my question is that how do I frame a agreement for above mentioned conditions.