1 On registration of property in June 2010, the ownership rights were passed on to you. Hence, June 2010 should be taken as the reference month and year for calculating the cost of acquisition. If there are additional expenses after the registration, they can be considered as cost of improvement.
2 If you are claiming exemption u/s 54F, you need to invest entire sale consideration. If the existing loan is repaid, to that extent your investment u/s 54F gets reduced and you will be entitled to proportionate exemption. If you are planning to get exemption u/s 54 or 54E, you can deposit your capital gains amount.
3 The capital gains is computed by indexing the cost of acquisition.
4 The interest on capital gain account deposit is taxable.