Your first question was answered when you asked the question in the thread "Half-mile long Canadian."
Regarding VIA's lease (with option to purchase) five Amtrak 10+6 sleepers, I have been told by VIA managers that it was indeed the then sleeper shortage that caused that. That was before any Renaissance sleepers were in service. The summer Canadian took all of the Manor cars. The Hudson Bay was using Chateau cars (usually only one per train, as they now normally use only one 10+6 sleeper per train.) The Toronto-Montreal Enterprise used Chateau sleepers (two per consist.) The Chaleur did (and still does) use anywhere from two to five Chateau sleepers. Of course, the three consists of the Ocean used the rest of the Chateau sleepers. There was such a shortage that between two and four sleepers were short-turned at Moncton. There are only 29 Chateau sleepers in the fleet, so you can see how difficult it was for VIA to keep all the trains with their needed consists. By the way, the 29 Chateau sleepers are the entire fleet as ordered by the CPR. It is the only type of car that has not lost some of its type. I believe there are 40 of the 42 original Manor sleepers left.