You will need to go to Samui Immigration to transfer the existing stamps from your old passport to your new passport. IF YOU ARE ON A VISA (a physical sticker or stamp that says "visa"), you do not need to do anything. If you are on an "extension of stay", you will need to get the stamps transferred.
> Do i need to get a new TM30?
No.
>is there anything else I might need to have prepared with a new passport?
You need a form to request the transfer. FOR BANGKOK IMMIGRATION, you can use this form:
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I do not know if it's accepted in Samui.