Inspect a PDF (iText 5)

iText can tell you more about a PDF. What is the size of a page? Which measurement unit is used? All of these questions can be answered with a simple example using PdfReader. Would you like to have these reference answers available to you at any time? Consider downloading the entire book 'The Best iText Questions on StackOverflow' for free!

I have some code that reads pdf files. The code fails saying that there's an "InvalidPdfException: PDF header signature not found".
I have a bunch of PDF files that I read into a byte array one by one. I then pass these byte arrays to a PdfReader instance. Now I want know the dimensions of each page in pixels. From what I've read so far it seems by PDF files work in points, a point being a configurable unit stored in some kind of dictionary in an element called /UserUnit .
I have a PDF, and I want to get the width and height of each page using iTextSharp.
I have a PdfReader instance that contains some pages in landscape mode and other page in portrait. I need to distinguish them to perform some operations... However, if I call the getPageSize() , the value is always the same.
In Adobe Reader, the first pages of an ebook can have page numbers in the Roman number format. I would like to read these page numbers (instead of the indexed page number) with iText.
I have a pdf document, inside are comments lists inside rectangles and text boxes. I want to get values from Text Boxes with c# and itextsharp.
Requirement is to process a batch of PDFs one at a time and on success encrypt each of them with an user password. However, these PDFs were encrypted previously with randomly generated dynamic owner password (not known to any one) to prevent any edits.
I am using iTextSharp to analyze a form enabled PDF. I know how to navigate to the radio button control. I would like to analyze the individual radio buttons.
Is it possible to get the author of a free text annotation using iText? I can retrieve the /Type and /Contents , but I can't find a way to get the author.
I am using iTextSharp for searching internal links in a PDF file. I already have code to find external links, but I don't know what to do to find internal links...