You should check out
these answers.
To open in a new window, use System.Diagnostics.Process.Start(). It will open Acrobat Reader.
To open in a panel like you said, You can use a browser. This will be just like having a PDF in IE or Firefox or whatever.
Unless I'm wrong, I think that PDFs are not open-source. So i'd be difficult to implement your own PDF reader. There's also a lot of PDF versions that would complicate things.
Hope it helps.