Topless sunbathing is fairly common among western women here on many beaches.
Though i doubt you will see a Thai woman going topless it is generally tolerated. Use your own discretion but do try and wear more than just a Bikini when in town/on the beach road.
And Nicke is easy to spot - he's the one getting his ass whupped at Backgammon!
He will also introduce you to any other board members who are present - enjoy your stay.