Xiamen to Gulangyu

I am visiting Xiamen in early September and would like to visit the Gulangyu Island from my hotel Intercontinental Xiamen. I am a bit confused on what I have read so far on how to reach the island and how to get back.
Do I have to leave from Dongdu ferry terminal? How does it connect by public bus from my hotel? Do I have to return to the same ferry terminal? Can my hotel prebook a ferry ticket for me? apologies for all these questions.