Is there a specific website that has a complete history and disposition of VIA Rail passenger cars as well as pictures?
I've yet to encounter such a site. The only document I use for Via Rail rosters is the Canadian Trackside Guide, published annually by the Bytown Railway Society. (Alas, no pictures.)
http://www.bytownrailwaysociety.ca/sales.htm
The book contains information on pretty much any and every piece of railroad rolling stock in Canada, plus radio frequencies, maps and schedules.
The Society encourages people to purchase the guide at local retail outlets (hobby shops, railroad museums, etc.) -- they charge a little extra if you order direct from them.