The route around the north side of Lake Ontario is Canada's most populated area , and traveling through requires planning to avoid the gridlock. Mid afternoon on a Tues. Wed or Thurs. would be best.
Travel through Quebec and northern New Brunswick , requires some knowledge of French as road signs aren't bi-lingual. Get your vehicle height and convert it to metric , and post that number on the dash , to avoid panic at the first underpass.
PEI & Nova Scotia/ Cape Breton Island, are well worth the drive to get to them , but JMHO: avoid the route around the Gaspe peninsula , some of the roughest road in Canada, and the only place I've seen a warning sign , that you may be washed off the road during a storm.
Bring your Passport, and leave your firearms at home.
For info , on what you can cross the border with , visit this web site.