I am a greencard holder, I plan to go back to Shenzhen for a short visit. I have several questions related to the upcoming trip:
1, Can I take flight to Hongkong and then take train from HK to Shenzhen? If so, are there any procedures involved at the HK custom and Shenzhen custom?
2, How long it normally takes from HK to Shenzhen by train or by other means of transportation?
3, When I come back to US from Shenzhen via HK, are there any specific procedures in Shenzhen and HK? Do I need to present any documents at the customs?
Many thanks in advance.