The Package Explorer utility provides the ability to open an Open XML package and browse through the relationships and parts. It supports navigation of embedded sub-packages and uses an object model that provides a clean separation between the UI and the packaging model.
Open XML Objects provides an object oriented framework for working with various Open XML documents. It shields you from the underlying XML and zip structures, allowing easy and intuitive document generation and manipulation.
Here is a basic sample to host an InfoPath form inside of Windows Presentation Foundation. This sample shows how to use the WindowsFormsHost to embed the Microsoft.Office.InfoPath.FormControl in a WPF application.