Capital Gain on redevelopment of constructed house

Dear Sir, My father purchased Plot of Land in 1979 and constructed house in 1980. Approximate amount of Land was Rs. 27000/- & Construction was of Rs. 200000/-. The whole bunglow was decided to demolish in 2012 and decided to go under redevelopment with a builder. Market value of a plot in March 2012 is Rs.11375500/-. Builder agreed to give 4 Flats in consideration. No any other consideration other than the 4 flats. Out of the 4 flats, my father transferred by Gift deed 3 flats to 3 sons and one kept with himself. Now in 2016, he sold the flat owned in his name after 36 months and ready to invest in NHAI Bands till December 2016. Question 1 : Is capital gain payable on transfer of Land against Development right ? whether is it exchange of Assets? if Capital Gain is payable, then in which year, 2012 or 2016? Question 2 : is capital gain payable on transfer of flat? what will be cost of acquisition for flat? Question 3 : the Plot is sold, Constructed house is demolished and flat is received as consideration. Now under which section exemption is eligible 54 / 54EC / 54F ?