Selling of plot and purchasing of flat.

Dear Sir/Madam My mother gifted me a plot 3 years ago and I hold the gift deed. we are planning to purchase a flat on my name, by selling the plot and also get a home loan on my name for the difference amount. both my mom and I do not hold any house on our names. both plot and flat are in hyderabad. I have few questions, pray your advice in understanding the things. 1) the plot buyer is a broker/builder, as per him gift deed has to be cancelled so that he can sell plot to others, otherwise end party would not get bank loan. should gift deed be cancelled? 2) if gift deed is cancelled, then plot owner would be my mother right? she will get the sale proceeds on her name. does she has to pay any tax/capital gains/anything? 3) what ever the amount she gets after selling the plot can she give me freely so that i can purchase a flat on my name? do i have to pay tax/capital gains or do i have to consider any other thing? 4) plot vendor and purchaser both executed promissory note, Rs X amount was paid as a token of advance. in the promissory note it has been mentioned that purchaser would register the plot in 45 days since the date of promissory note. revenue stamp was affixed and i signed across it. my mom and dad are two witnesses. I dont hold the original document, i hold photocopy of it. a) is promissory not legally valid? b) if so how long will it be valid? c) if both parties agree to cancel the deal before making the sale agreement , what are the steps to be followed by both of us to make sure that promissory note which was executed is no longer valid? d) purchaser told us that he would come for sale agreement in 10 days. i learnt that sale agreement has to be registered to make it legal. is registered sale agreement benefial to me or to the purchaser? if he denies for registered sale agreement then how can i cancel the deal? what will be the fate of the promissory note? e) if both parties enter into sale agreement and still agree to cancel the deal without the registraion, then how to cancel sale agreement? f) only promissory note was executed. neither sale agreement nor registration is executed in 45 days as noted in the promissory note. can i return the token advance to the buyer and sell this plot to others? g) if sale agreement is executed but the buyer did not register the plot in his name as per the agreement, can i return the amount which i received to the buyer and sell this plot to others? h) is registered sale agreement still be valid after the plot registration? i) what is the best model for registered sale agreement so that vendor and purchaser are safe? j) lets say Rs Y is mentioned in the sale agreement, if purchaser is getting registered for amount less than Y, the difference amount would be black amount right, because it is not recorded in the sale deed? k) what ever the amount is agreed by both parties the same thing has to be in the sale deed right? we both are agreed for Rs Y amount, i dont want any black money, so what mode of transactions (cheque/DD/NEFT/RTGS/CASH/...) are safe? along with the amount, mode of transaction should also be recorded in the sale deed?