Yes you can invest the long term capital gains in a new house property within two years from the date of sale of property to claim exemption under section 54 of income tax act. 

Yes it can be taken

The construction need to be completed in 3 years from the sale of property and you are required to deposit the amount of gains in the Capital gains account scheme with public sector bank before filing of returns.

Construction you can start later but must complete within 3 years from date of sale. Show in yours returns invested in under construction property. Purchasing plot is also part of construction.  

Section 54 : To claim full exemption the entire capital gains have to be invested..

In case entire capital gains are not invested - the amount not invested is charged to tax as long-term capital gains.

This exemption will be reversed if you sell this new property within 3 years of purchase and capital gains from sale of the new property will be taxed as short-term capital gains

You can purchase  a house within one year before and two years after the transaction date or construct a house within three years from the date of transaction.

You must invest in residential house property not land. 

Balance amount of capital gain if any not utilised before filing of return should be invested in capital gain account in PSU bank and a copy of deposit receipt must be attached with the return. 

The benefit canbe claimed by purchasing or by constructing a residential house.

2) the benefit of section 54 is available if the capital gain arising on transfer of residential house is invested in another residential house. The benefit of section 54 is not available if the capital gain arising on transfer of house is invested in capital asset other than a residential house.

Yes in next one year you can build the house on that plot. Plus need to check actually how much long term Capital Gain Index ratio.

If its needed than only you can reinvest otherwise you can buyer NABARDs Bond as well accordingly to Long Term Capital Gain Tax.

U/s.54 of the Act, LTCG / STCG can be claimed as follows:

     - If you invest money in residential purpose and after sale you purchase for residential house / property u can claim exemption.

     - If you invest money in commercial purpose and after sale you purchase for commercial property u cannot claim exemption.

 Yes deduction can be claimed for purchasing the property after selling the house by investing long term capital gains.