Documents require for china visa application. Best way to travel to Shenzen.

We will be travelling to Hong Kong, Shenzen and Macau next month. Hope you can answer my enquiries.
1. My son is 18 years old, studying and living in Singapore at the moment. Can he apply the china visa using only his passport without air ticket and hotel reservation? 2. Is it convenient to travel to Shenzen direct from Hong Kong airport? What is the option and cost? 3. What is best way to travel from Macau to Hong Kong airport on the 25 Dec? Do we need to buy our transportation tickets in advance since it is a Christmas day? Our flight is 8.05pm. Thanks in advance.