Ferry from Guangzhou to Hong Kong

Hi there,

my train from Bejing arrives at 18.01 on the 26th of July in GZ South (I just booked the train ticket via your homepage). I would like to travel to Hongkong via ferry. As far as I can see there is no ferry transfer in the evening therefore I would stay a night in GZ and take a ferry in the moring of the 27th of July. I would take a ferry from Lianhuashan Port to China Hong Kong City Port (any better suggestions concerning the port?).

My question:
-can I book the ticket in advance? (I do not speak chinese and am afraid to fail buying a ticket). If one can buy a ticket in advance, where?
-I have a carryon bag and a pice of luggage (aproximately 20 kg). Is there a check in for luggage? do I have to pay extra for a normal size suitcase?

Thank you very much!