If you enter Thailand with a new passport, you simply show both passports at immigration, and you’ll be stamped in on the new one. You can then visit the local immigration office later to have the stamps transferred.
You have already been provided with a response on another site. Accordingly, the Hua Hin Immigration Office accepts applications up to 45 days prior to the expiry of your current permission to stay.
Should the application be submitted with 30 days or less remaining on the current permission, you may be assured that both the income certification issued by the embassy and the extract from the Amphur confirming the marriage will be deemed valid and accepted by the immigration.
To fulfill the financial requirements, you will need to provide evidence of funds amounting to 500,000 THB in a bank account. Regarding the visa validity, it is issued for a period of five years with a permitted stay of 180 days per entry within this timeframe.
If the immigration office in question accepts monthly transfers of income or pension from abroad as grounds for an extension of stay based on marriage, it will most likely also require that the transfer be recorded as an international transaction. While some applicants have managed to achieve this when using Wise, it is something you will need to verify independently.