link annotation

I want to change only zoom property of links.
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...
We create a file with specific /XYZ destinations and we change the zoom factor of these destinations. These examples were written in the context of questions such as: How to set the zoom level of a PDF using iTextSharp? How to change the zoom factor in link annotations?
I would like to add a link to an existing pdf that jumps to a coordinate on another page.
I have an existing document, onto which I would like to stamp an image at an absolute position. I am able to do this, but I would also like to make this image clickable: when a user clicks on the image I would like the PDF to go to the last page of the document.
Is anyone out there able to create a clickable annotation that has an irregular shape?
Adobe enabled us to set a base url for each document. We really need this in order to deploy our documents on different servers. But we cant seem to find the right code to do this.
I need to set the zoom level to 75% in a PDF file using iTextSharp.