Is the canal any different than a river?
I play using the canal the same as a river. I couldn't find any official answer in the rules, and we've had some debates about why they would put in a canal specifically if it's just the same as a river. We came to the conclusion that it was put in there for "geographical accuracy" as opposed to any effect on the game play.
Can both players import from the same foreign city (essentially making the other foreign city useless?
Is the first cube added to the foreign cities during the first phase of the first turn or at the end of the first turn?
Each foreign city starts with a cube initially (and the supply tracks are full). A cube is moved from the supply track into the foreign city at the end of each turn. The last cube gets moved from the supply track at the end of turn 6. Because of this the supply track is a good way to keep track of how many turns are left in the game (empty supply track = one last turn).