... on either question.  Sorry.   When we had to georeference our own imagery, we used a tool from www.tatukgis.com.   It was the Aerial Imagery Corrector, but it isn't free.    Have also done some things with Blue Marble Geographic transformer.    If you are up for command line tools, and free, there is a open source project called GDAL that has a very powerful set of tools.  With these tools, you can clip sections out of a SID image, etc.

And I don't know of free imagery sources for Canada.   If you find some, I would appreciate it if you could let us all know.    In fact, I don't even know of "pay" sources for Canada imagery.