Dynamic Email-Excel Power Automate

I need a Power Automate cloud flow ready by November 5th that will handle an incoming e-mail, always from the same sender and with the same subject line. The flow must pull the attached workbook, ignore any introductory text that precedes the actual table, and detect the first data row dynamically (the number of header rows can change each time). Once the table has been isolated and converted to an Excel Online (Business) table, the flow should insert one additional calculated column whose value is derived directly from other cell values in each row. After that, the updated file has to be sent by email.