We are manipulating our Word 2007 documents from .Net using Word Interop. Mostly doing stuff with fields as in:
For Each f In d.Fields
f.Select()
//d
I'm not sure I'm using the same environment as you, but to go to the start or end of the document here's what works for me:
Private Sub moveCursorToStartOfDocument()
w.Selection.HomeKey(WdUnits.wdStory, Nothing)
End Sub
Private Sub moveCursorToEndOfDocument()
w.Selection.EndKey(WdUnits.wdStory, Nothing)
End Sub