>
>1. Is there a function in .NET (C#) that works like the FileToStr?
>2. If so, will VFP StrToFile function be able to read that string value created in C# and still create the PDF?
>

Yes. Take a look in the System.IO namespace, specifically the File class. There are 4 methods here you'd probably interested in:

FILETOSTR() - 

byte[] file = File.ReadAllBytes(@"C:\SomePathToFile\FileHere.PDF");
string file = File.ReadAllText(@"C:\SomePathToFile\FileHere.txt")

STRTOFILE() - 
File.WriteAllBytes(@"C:\SomePathToFile\FileHere.PDF", file);
File.WriteAllText(@"C:\SomePathToFile\FileHere.PDF", file);