There is a VIA station (Canadian gov't subsized version of Amtrak) in the town of Gaspe - not too far from the lighthouse at the end of the trail. Take the train to MonctonNB (or Quebec City - I imagine it would be easier to get where you need to go in the States)
There are plenty of maps detailing the IAT route available for sale on the website posted by vaporjourney - but I'm not sure if there is a "Companion"-style booklet available detailing the services available in each town on route. Part of the adventure is find out what's available when you get there - I think the website also suggests possible mail drops if you want some certainty
As far as needing French - it's not an absolute necessity. The provincial parks the trail goes through (Carleton, Jacque-Cartier, etc) have bilingual staff. Learning some simple phrases may help, followed by a polite "Je m'excuse, mais je ne parle pas Francais" goes a long way.
Still highly recommend going all the way to Gaspe – it’s like walking to the ends of the earth.