If you are visiting in winter, fly to NB and drive to Mt Allison, or fly to Halifax and drive to Truro. You will want to avoid the Cobequoid Pass at all costs if you can during winter.
And driving throught Quebec during Winter isn't much fun either, especially now that snow tires are mandatory. Nice little ticket if they catch you without them, even if you are just passing through.
Simplest way really is to fly to Halifax, rent a car and drive the 35 min to Truro on only 1 stretch of divided highway. No tolls, no lane changes, no fuss.