Incorperate iAnnotate into my iPad App

So I was surfing the web on my iPad and I saw a link to a PDF that I wanted to view. I clicked the link, the PDF downloaded and opened. The first thing I noticed while viewing the P开发者_高级运维DF is a button I could tap to view the PDF in an existing App on my iPad called PDF reader. That got me thinking, I want to make an iPad app that handles versioning of PDF documents and I want to allow for annotations but I don't want to spend that much time learning how to annotate PDFs.

(1) Is it possible to have users download PDFs to my app's subdirectory and have my app open another app like iAnnotate to do the annotating? Then have iAnnotate save it's changes back to the PDF that is in my app's subdirectory.

(2) I know apps can register as handlers to certain kinds of files. If I used something like [Application OpenURL] could I pass the path and file name of my PDF document and have iAnnotate open the PDF?

(3) Lastly, is there a global repository of PDFs that all existing apps can access? That way I would not need to open iAnnotate from my app, I would download directly to the global repository and just instruct the user to open iAnnotate on their own and view/edit annotations.

I found my answer with this link here from another question. The only thing I need to figure out is if iAnnotate has the permissions to modify the documents in my subdirectory. But I guess that's another question.