Ross,
All 40 Eaton cars were of the same pattern, large turreted vehicles on the Jeffrey Quad chassis. The Scout car was, as mentioned earlier, an open Russel-Knight tourer with an armoured hood and partial front doors.
I do not know anything about the Polish army in Niagara, but there are several web references available, like
http://www.electronicmuseum.ca/Poland-Canada/lepan.html
For more, just enter 'camp niagara' (or 'niagara camp') and 'polish' in Google and away you go.
Gord