<p>I'm looking for a library to read a SWF file and let me parse through its actionscript and header information. Is there anything out there that will work?</p>

I do not know of any libraries (including .NET) that let you read and parse (or reverse engineer) the contents of SWF's files. The ActionScript you are referring to is compiled down to byte code during compilation so you will not find the actual ActionScript source code in the SWF file.
For more information in the SWF file format I suggest you have a look at the
official specifications
.