Regarding transport in Shantou, particularly train tickets from Guangzhou, there are some nice people (no English though) just near where all the bars are that have a possibly somewhat illegal bus station - but also a very useful ticket office. I have heard that people can’t buy train tickets for the big holiday periods but I have bought from there twice, once for National Day and once for just before Spring Fesitval, they only sell tickets from 6 days before departure but I have both times got the seat (bed) I wanted.
Longhu Ying? Bus Station, Ying? Rd. Phone:8367099
Appartently they can also book tickets from Xiamen train station but I’m sure they said that wasn’t possible last time I asked.
PS Don’t bother with the Shantou train station unless you’re going to Meizhou, which is the only stop quicker than the bus.