Let me answer all your questions.
The same way as in the rest of Ignition. Use the datasources that have been configured in the Gateway and use the system.db.* query functions to send queries to databases. Look at the examples for any of the query functions in the Ignition User Manual. They are used no differently in WebDev Python scripts.
Accessing tags in WebDev Python scripts is also done the same way as in any other script: using the system.tag.* functions.
Typical Ignition Python scripting, accessing tags, databases, Python user-libraries etc. is the same in WebDev Python scripts.
Yes, that’s what the WebDev module is for. WebDev stands for Web Development.
The WebDev module is for making websites that are served from the Ignition Gateway. The data resources in Ignition such as tags and database connections are available to the Python scripts that you write to generate the webpages and web data feeds etc.
The WebDev module provides documentation for the web resources and functionality that it exposes and gives examples of how to use them.
Yes, it is! I can’t wait until someone comes along and asks me to build an Ignition-based website!