i've never been to vermont but have heard great things about their skatepark and spots. might be worth going if you have the time.
for skateboarding, there is a lot to do in MTL.
for skating, check out the new MTL plaza and van horne skatepark. if you're into transition, the vans park could be worth checking out (it's besides the big o).
the peace park is worth checking out too, given its history.
dime store is close by peace park.
i am pretty sure there is a skatepark in trois-rivieries. there will definitely be some in cities nearby. no good shops there though.
quebec city has a lot of touristic things to do. the skate plaza has some good options but there are more and more smaller parks being built there. skate spots are scattered all over. exo would be the shop to check out.
skating wise i am not sure what there in the gaspé region, but you'll have a blast eitherway. it's a good trip.