Yes, they did finish. It was a year before the bombs fell. Late in the year.

You do realize that is the same time they finished annexing canada, right? And that the US started to annex Canada in 2067, therabouts?

is thier any specification that there wernt any other vault corperations in other countries or that vault tech wasnt internation or didnt build private vaults or military vaults or government vaults or industrial vaults ect?

No, there's nothing specific saying that Vault tec was the only one, and I think it would be illogical to think so.

There probably were other vault companies willing to build private shelters for the rich in the US, given the ultra-capitalist nature of the society...

A group of survivalists had their own underground shelter in the Ghost farm at Modoc.

Whether or not other governments developed similar programs isnt said, but given that North Korea's subway system is designed to double as deep bomb shelters, and the US' building them (which could be seen as an agressive stance), I think its logical to assume that some other countries had similar projects.

Now if we are going on the assumption that the "Diefenbunkers", the RCN, RCAF and Cdn. Army & Cdn. Civil Defense Bunkers were used, how exactly were they integrated into the Enclave Social Experiment, since the above bunkers in question, had quite a different purpose, with their primary purpose having been to protect senior government officials, members of Canada's General Staff and citizens deemed important to the survival of their nation, so I have to wonder, did some of these assets instead get assigned to the Enclave, for the protection of their own personnel?

It would make sense; and would explain how they got to DC after their oil rig was blown to peices. After all, it's easier to recover if you don't have all of your eggs in one basket.