Where is Shenzhen ?? Is it South of Beijing ?? From Shanghai - in which direction

It is a city in south China. It is in the south of Beijing and southwestern Shanghai.
There is around 2,400km from Beijing to the city and the distance from Shanghai is around 1,600km.

Tipping in China

You answered 2 questions I asked - extremely well. Thanks.

Wish to bother you with one more question:

What is the tipping etiquette in China ?? Taxi's, bellboys, restaurants etc.

Sorry for the bother

It depends on your own, I think.
If you think they work hard and want to tip them, you can do and how much you want to pay is not fixed.
If you do not want to, you can save the money on your own.
For my suggestions, you can give some tips for the bellboys in the hotel, but for the restaurants and taxis, it is no necessary to do so.