<p>In ASP.NET, I have an XML file (within my project) that I would like to deserialize.  FileStream objects do not allow you to open a file via URL.  </p>

<p>What is the easiest way to open the file so that I can deserialize it? </p>

Generally, we put it all in one file. This isn't Java or C++.
Start with a single file until you get some more experience with Python.  Unless your files are gargantuan, it will work fine.
For example, Django encourages this style, so copy their formula for success.  One module for the model.  A module for each application; each application imports a common model.
Your Database and superclass stuff can be in your
```
__init__.py
```
file, since it applies to the entire package.  That may reduce some of the circularity.