Rules regarding borrowing for trading

pl divulge whatever is the latest on the “borrowing for trading front”.this is a gray area.u cant borrow money without the responsibility of paying it back…?if u take a loan from a person to trade…it is your responsibility to pay it back…under such scenario what is the highest rate of interest legally allowed to be paid to the lender?..becaz lets face it nobody is going to give you money on 2%monthly interest…i ask this because under normal scenarios borrowing on 10% interest per month is seemed as something illegal…however in stock mkt an individual proficient hedge fund specialist trading large amt of money can easily surpass this target…whatever is the excess he gets to keep it…also he is trading with the money borrowed as loan…need clarification on this asap…with tax implications too…

Check this - http://zerodha.com/z-connect/tradezerodha/margin-requirements/online-pledging-of-stocks-for-trading-fo

Can I lend money to friends and family without interest.

Is there any tax complications ?