Do you pay any form of tax if you are the beneficiary of the life insurance of your brother? If so,what % of the total amount?

Life insurance benefits probably aren't taxable at all.  This is because the premiums that were paid for the insurance policy were made from after-tax income (they weren't deductible), so that taxing the benefits would essentially be double taxation.

The exception would be if the brothers were business partners, and the insurance policy had been taken out by the business ("key man insurance") and the premiums deducted as a business expense on the partnership's books.  In that case, the benefit would be taxed, since the premiums weren't.