Ltcg of sale of second home

Sir, 

1. If we sell a second home, after 5 years of purchase, hope the tax rebates (principal / interest) enjoyed will not be reverted.

2. If cost price during purchase before 5 years = 60 Lakhs (registered value of the deed) ;  CII : 280 / 220 = 1.27 ;  Indexed cost = 60*1.27= 76 Lakhs;

     If Selling Price : 80 Lacs >> LTCG = 80L-76L = 4 Lakhs.

     a) Is LTCG tax applicable is 20% on 4 Lakhs? 

     b) If the assessor is in 30% slab, Still LTCG applicable is 20%

     c) If the assessor pays 20% tax on 4 Lakhs =  80,000, Then is he free to invest the sale proceedings 79.2L (80L-80K) or

         he need to invest this amount in buying next house / Govt. Bonds for saving tax only.

     d) Should we mention this entire corpus(79.2L) as income, and where to declare in return.

     f) If the above corpus(79.2L) is invested in FD/POMIS etc., hope only the interest earned attracts tax.