TOPIC:

How to get zoom level or get width and height of PDF canvas?

see [PDFV m_zoom_scale]
width and height of canvas for whole Document:
[PDFV m_docw];
[PDFV m_doch];

all of these member are not public.
so you can define methods to return these member in PDFV class
and define new methods in PDFView class, return to higher level classes.