My parents will go to Hongkong and wants to cross to Shenzhen. Will they get the visa on arrival for China? and which border should they enter? how long they can stay in Shenzhen? They planned to stay 4 nights in Shenzhen. How much it will cost them for the visa? And please suggest the best transportation to go from Hongkong to Shenzhen, in money wise as well as the time.