Make ferry reservations as soon as you can confirm your arrival and departure dates, especially departure. We booked our departure 2 days in advance and we were bumped back by 6 days due to storms and hurricanes coming up the east coast.Our original departure was Aug 26 night crossing and we left Sept 1 Night crossing. Nothing we could do about it. We were booked on Port aux Basques to North Sidney.(7 hr crossing).The folks that had booked long in advance were booked on the next available crossing and they worked through to the shorter bookings, until they had the backlog cleared up.
Roads are decent just like the rest of Canada except they seemed narrow in parts, with some frost heave pot holes and repairs, gravel roads to some of the provincial parks aren't too bad, but watch the road legend on the road map, as some of the "short cuts" are gravel and slower than the paved roads.
Make sure to give yourself lots of time. We had 3 weeks in 2015 from the time we left Southern Ontario until we got back. I drove long days and we were 2 days from home to the ferry and 2 days from the ferry back home. On the way home DW pulled out the notepad and said what do we go back for. 2019 we were gone for 12 weeks, through Quebec and Labrador then to the island and I think we pretty much did it all, but we could probably go back for another summer and do more.
And Jaxdad is correct we still saw snow beside the roads in mid July!