I am traveling to Beijing on the 22nd of Sept 2013. I intend to buy stuff for family on my way back

The leather and the silk will work in India, but I do not think the mobile can work normally in your country.
No duty needs to be paid when buying them. If you do not take much when you get out of China, you do not need to pay duty.
All these kinds of items can be found in either of the three cities, so it is suggested to buy your stuff in the last city you visit.