Capital gains !!

Sale Considration of property is Rs 37,00,000.

Cost of Aquisation was Rs 17,00,000.

Capital Gain after indexation is Rs 16,00,000

1. What is maximum cost of improvement can be shown in above case ?

2. Do we require bills for cost of improvement if it seems reasonable and how much amount seems reasonable ?

3. specify the amount of maximum brokerage which can be paid in above case (paid by cheque with bills) ? 

NOTE : property is puchased 38 months ago