Required - capital gain tax solutions

Hello Friends....

My frined's father sold a residendial property and got some capital gain tax of around Rs 10 lacs. Now he was advised to reinvest in a residencial flat or NHAI bonds to save capital gains.... when he discussed this with me I had few doubts as under:

1) If he invests in NHAI bonds for 3 years then after the maturity will he be again liable for capital gain tax on the capital gains or interest he will make ?

2) If he buys a residencial flat and sells it again after 3 years with a profit above indexsation will he be again liable to capital gain tax ?

3) Can he buy a house on a agriculture ladn along with the land to save capital gain tax ?

4) Can he buy agriculture land from his own source and then built a house on it with the money allocated to save capital gian tax ?

Any inputs and sharing of knowledge will be usefulll...

Thanks in Advance....