SQL Server 2008 :: Size Limitation For XML Data Type?

I've never worked with the XML data type in SQL Server, although I know its been there for a few iterations of SQL SErver. Now I've got a situation in which it might store some configuration data as XML, since that's the way it comes. (We had thought about storing the data in a VARCHAR(MAX) field.)

The first question is does the XML data type have a size limitation? For example do you do something like:

ConfigFile XML(1000) NULL

Or is it just something like this:

ConfigFile XML NULL

The second question is persisting the data to a file. As the name I choose for the variable suggests, we want to save the data from a configuration file into a SQL Server database. How do we go about doing that? We'll be developing a C# application, it will read and write the data both from the SQL table and the user's local HD.