Mr Mark;
Just came back from the Maritimes on Friday so everything is still pretty fresh. Drove through Quebec, New Brunswick and Nova Scotia. A bit off topic since I wasn't in a caravan.
First the roads - I was on the four lane divided highway all the way (from Ottawa Ontario area), traffic was not an issue except around Montreal (used route 30 by pass). There is one 2 lane section for about 40 KM south of River de Loup but with lots of passing lanes. Speed limit is 100 kph on the four lane and 90 kph on the two lane.
Quebec highways are mainly good but there are some rough spots. Note that all their highway signs, construction signs and other notices are in French only - sometimes you can guess but other times you will have no idea what they mean. I don't speak French and normally go through the US when heading east.
New Brunswick highways (4 lane divided) are OK but terrible around Moncton and some other areas! They seem to have neglected the roads for the last several years. Make sure everything in your cabinets are secured! Speed limit is 110kph. New Brunswick is the only officially bi-lingual province in Canada and all road signs are in French and English so you won't have any problems.
Nova Scotia highways (4 lane divided) are excellent, speed limit 110kph.
Ontario highways are average but very very busy with truck traffic between Montreal and Toronto. Speed limit is 100kph. Note that commercial trucks in both Quebec and Ontario must be governed at 105 kph but they will still try and pass you if you are doing slightly above the speed limit.
Only Quebec has rest stops along the highway where you can pull of and take a break (they have washrooms)- lots of room for a MH. There is usually a canteen truck at the stops but they very pricey.In the other provinces there are lots of truck stops where you can take a break. Also the tourist information centers for New Brunswick and Nova Scotia are worth stopping at with lots of room for RVs.
Getting fuel in the Maritimes is a bit challenging as you can't use the truck stops as they are taxed differently. But you can always park where the trucks park and walk over and look at the regular fuel pumps to see if you can get in and out. I'm sure the wagon masters have all this figured out.
Diesel cost me between 99.9 cents and 101.9 cents per litre (roughly $2.80 USD per gallon)and prices were dropping. Most maritime provinces regulate the (minimum) price of fuel and it only changes weekly (or less often - not sure).
Each campground that I stayed at did offer 50 amp service, though not all sites had it. Some campgrounds had tight turns for a 41' 9" MH towing a car but we managed.
We stayed at Scotia Pines campground just south of Truro NS for 7 nights. Friendly staff and very clean campground (Good Sam member).
Truro puts you in the center of NS, an hour from Halifax, 90 minutes from Peggy's Cove and 1 hour from the Anne Murray museum (DW is a fan) and the mine tour in Springhill. Probably put around 2000 km on the toad exploring the local area.
Campsite fees (water, electric and sewer) for 3 adults ranged from $38 to $46 per night CAD - roughly $27 to $33 USD depending on the exchange rate. The most expensive place for both fuel and camping was Quebec - we just drove straight through on the way back, only using the rest stops.
There is one toll on the four lane in Nova Scotia at $5.25 for RVs, includes MH towing, fifth wheels and TT. Quebec has a toll on Route 30 that cost me $7.40.
I drove (in my car) to Newfoundland in May (1st granchild)and the roads there were average with lots of passing lanes. I lived in Newfoundland off and on for 14 years while in the army (my wife is from there) and loved it. Many beautiful unspoiled places to see and lots of history. The only problem is the cost of the ferry for the MH. As a veteran I don't have to pay the passenger fee for myself and up to 3 others, but it still adds up.
HTH helps, go with a caravan the first time and I'm pretty sure you'll come back on your own to explore later.
Chris