Questions: Traveling by Train

Q: Concerning the trains, is it possible to have "first class trains" with 2 persons in one sleeping cabin?
A: The first class (soft-sleeper class) is 4 persons in one sleeping cabin, no private bathroom. Only on trains from Beijing and Shanghai to
    Hong Kong, 2 persons in one cabin are available.

Q: Will it be possible to make a reservation for train tickets?
A: So far, the train tickets could not be reserved can only be bought a several days before departure.

Q: Any trains going from Hong Kong to Shenzhen? And how about the train from Shenzhen to Guangzhou?
A: Yes, There are frequently trains between Hong Kong and Shenzhen, almost every 5 minutes. But the train only comes to the border, you
    need to cross the border and through the custom afterwards.
    From Shenzhen to Guangzhou, there is a train leaves every an hour. The railway station is just a few hundreds meters from the border.