Clearances shouldn't be a problem on main routes. All bridges are marked. Some highways with older arch type bridges may have signage that says trucks must use left lane.
Electrical will depend on what type of parks you stay in. Most provincial parks don't have 50amp service and many won't have full hookups. Electrical only with water fill and dump stations are more common. Private parks and some conservation areas will have more services. Depending on time of year you will need to reserve sites in advance. In Ontario the provincial park bookings open 5 months in advance (at 7am) and book up quick.
Many people in Quebec speak English so you shouldn't have any problems. You'll find a lot of places to be bilingual. It's only when you get further north and into small towns where people are more French.