1. The clause no.5 & 6 are sufficient to bind the purchaser in making repayment to BOI in the current account of the builder towards the loan taken by the builder for constructing the said flat. Actually the BOI is insisting you to pay more than what they have advanced towards construction of the said flat on pro-rata bases since it is collecting the profit of the builder also while insisting deposit of the entire amount.
2. the above two clauses are protecting the interest of the lending Bank and is completely to the one sided being to the Bank's side.
3. There is nothing to protect the interest of the buyers since after completing receipt of full payment (from all the flat buyers) towards the loan the bank will not take any further payment (since the rest amount of sale proceeds will be towards the profit of the builder which may be even 100% of the loan taken i.e. if all the buyers pay 50% of the price, the Bank's loan given to the builder will be repaid) and thereafter if the builder takes another 30% to 40% from the flat owners and runs away without registering the sale deeds for the flats, then the buyers will be at a larch.
4. There should be tripartite agreement with the builder, the bank and the buyer wherein the buyer will agree to deposit the entire sale proceeds to the lending bank and and the bank will have no claim on the said flats if the deposits of the sales proceeds are directly deposited with the bank.
5. If the bank does not want to enter in to such agreement, they should give NOC on that line only and the buyers will have no responsibility for any act of the builder towards the repayment.