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The property must be registered at stamp duty or actual sales consideration, whichever is higher.
Also, capital gain will be charged on sale consideration or stamp duty value whichever is higher.
1. Yes, it would create problem at the time of scrutiny.
2.Yes, the buyer (you) will have to pay stamp duty on the difference between the market rate (actual rate) and the circle rate at the time scrutiny If this case is caught up.
Next consideration is cost of acquisition when you will be selling the property. You shall only be eligible to claim the costs that have been mentioned in the sale deed registered Thereby the capital gains would be more and more taxes shall have to be paid.
3.You need to deduct tds on actual sales consideration.
4.As per ownership of property.
You are required to file two Form 26QB and pay the TDS according to the share of each joint owner in the property. - You are also required to file 26QB at the time of payment of each installment.
5.Yes, you should take the proof for the same.
It is advisable to take a phone consultation for detailed discussion.