Can only comment on question #2
When I bought my shares in Kimber it was while they were still only listed as KBR.TO in Canada. After they went on the AMEX my broker offered me the choice to leave things as they were or to switch to the AMEX traded KBX shares. The exchange was "matter of fact" one for one as if that was just simply understood.
Based on that I am quite sure that a share is a share is a share; whether purchased in Canada, on the pink sheets, or the AMEX. So I would say the answer to #2A is yes they are exchangeable. 2B I very briefly looked into a Canadian account with one of the U.S. brokerages that also has a Canadian side and received a letter saying, "No, I had to be a Canadian citizen." I don't know if this is true with other brokerages. It would take some research on the web to find a broker who will allow you to trade the Canadian markets directly. I believe it can be done.
P.