RVing in Canada is no different than in the USA, maybe some terminology. The same for highways and roads, probably fewer Controlled Access highways (Interstate). Gasoline/fuel is measured in litres (about 1/4 gal) and distance speed in kilometres km/hour.
1. Low clearance bridges, not a problem on main highways, possibly on some back roads.
2. Generally good, but can be bad areas.
3. Boondocking, you will learn quickly, just be more conservative with water and power usage. 50 amp service, at most campgrounds, but 30 amp will suffice 95% of time, just carry the adaptor.
4. Shouldn't be any major problems, just avoid driving in major cities, Toronto, Montreal (think Atlanta or Washington DC), in rush hours.
5. French, Quebec and northern NB. shouldn't be a problem in major tourist areas, they want the tourist $$, but in small towns, might be more of an issue, but generally they will try and work with you.
Campgrounds Last 2 weeks of June to Labour Day, reservations recommended for weekends, probably a necessity for holiday weekends, May 24, July 1-4, first weekend of August and Labour Day.
Sightseeing, let us know what your interested in, natural scenery, big city, history etc.
Ken
Edit Added, Clearances, I used a label maker and put the clearances on visible spot on the dash, in both feet/inches and meters, rounded off higher than the MH actually is.