What is important when preparing a WebConfig file for deployment?

When preparing a WebConfig file for deployment, setting the storageMode to "Auto" and the restrictionLevel to "ReadOnlyConfigFile" is important because it ensures that the application's configuration is managed appropriately in a production environment.

Setting storageMode to "Auto" allows Sitefinity to automatically select the best storage mode for the configuration settings based on the environment. This can help in optimizing performance and ensuring that configuration changes are handled correctly across different environments, such as development, staging, and production.

Additionally, adjusting the restrictionLevel to "ReadOnlyConfigFile" protects the configuration settings from being changed at runtime. This is crucial in a production scenario, as it helps maintain the integrity of the application settings, preventing unauthorized or accidental modifications that could lead to errors or downtime.

In contrast, ensuring all properties are set to editable or removing custom settings may not address the requirements for secure and stable deployment configuration practices. Backup entries might be helpful for recovery purposes but does not directly relate to the best practices for configuring deployment settings. Therefore, focusing on the storage mode and restriction level is key to a successful and secure deployment of the Website's configuration.