Haikou or Sanya Stay for 2 nights

Please advise if I only have 2 nights to Hainan Island, would there be enough time to arrive at Haikou and then go to Sanya on same day, stay for 2 nights and depart on early morning of 3rd day back to Haikou?

Is possible, can I get transfer to high speed train from Meilan Airport to Sanya? How much and how long is the journey? What about train schedule info?

In Sanya, which area is best to stay central and easy to move around city and to beaches.

Look forward to your advice, thanks in advance!