During the day many tourist boats come for snorkeling so the beaches can be quite busy. After about 3 to 4 pm when the day tourists have left the island is quiet and very peaceful and if you are lucky you can hear the waves from your bedroom. Only the resorts have 24h electricity, the budget places turn the generate on at about 6pm for a few hours.
There are daily boats from Koh Chang, Koh Mak and Laem Ngop (mainland close to Trat). Just tell them where you are staying and they will drop of you at the right beach/pier.
The island is very small and only has foot paths. It takes about 20-30min to cross from north to the south coast.
Chill, relax and chill some more. Maybe eat and go for a short walk. There's a footpath aross the island and there's a sunset point.
The few accomodations have restaurants and offer food. See 'Sleep'.