"Float" is just mid-atlantic vernacular for a river outing where you're tubing or paddling. It might be used other places too. I was never a fan of the term because it sounds kind of passive and paddling isn't passive!
Yellowcanoe, I don't know if Fort Kent counts as being close to Allagash, but First Mile Brewing company opened there I think in December. I haven't visited FK since then, but I'll definitely stop next time I am there. http://mainebrewersguild.org/brewers/first-mile-brewing-co/