HI! How to get from Xiamen to Shenzhen? How long? how much? and do we need a visa?

Well, you can go to Hu Bin Nan Bus Station or the Xing Lin Bus Station to take a direct long-distance bus to your destination. It takes about 9 h or a little longer. The ticket far4 is about CNY232.
As you can go to Xiamen, you must have had a China visa. It can be all the cities of China. So don't worry!