Detroit to Niagara Falls via Canada, what to expect?

Sounds like you have all your paperwork in order, the doc from the ex wife is a must. For food, usually it is harder getting food into the US, but right now poultry is an issue in Canada. Generally we avoid all perishables as opposed to trying to figure out what is OK and what is not from one week to the next. Guns are a no no- full stop. Pets should have vaccinations.