The softwood lumber dispute is an old one going back many presidents, and it would have come up regardless of who was elected in the US this time.  The dairy trade war...there isn't any.  It will probably be a focus for NAFTA renegotiations, but it was also a focus for the Euro zone FTA.  

Trudeau's approach should remain the same.  He cannot control what Trump does.  He should continue to respond as he has done so far...with logic and reason to defeat Trump's unpredicitable behaviour.  Any other response would be less effective.