Automated Property Valuation Model with Machine Learning

Create a Python script that integrates pandas and scikit-learn to build a comprehensive property valuation model using historical real estate transaction data from a Google Sheet. The script should automatically pull data, preprocess features like location, square footage, amenities, and year built, then generate a predictive regression model with cross-validation. Include error metrics, feature importance visualization, and a method to export predictions back to the original spreadsheet with confidence intervals.