I am planning a visit to Sanya Island Hainan in February 2020 asked by Dave Shepherd UK

I want to know if it still has a visa free option ? Do I need a Henan agency to apply for me ?
Will I need the invitation letter to from my friend if I am not stopping at an Hotel for the duration of my stay ?
and please clarify the cost.? Is there any option to visit the mainland by upgrade without a full visa and my Airport destination is Pheonix Intenational

Thank you