Instruction: Create a detailed plan for developing an Excel model that can simulate real-time updates of financial market data using external data connections and dynamic formulas.
Context: This question assesses the candidate's proficiency in integrating Excel with external data sources, utilizing Excel functions like WEBSERVICE or IMPORTXML, and creating dynamic formulas to update the values in real-time. The answer should detail how to set up data connections, manage data refresh settings, and possibly use VBA to automate updates and handle errors efficiently.