$1:
Does his hearing problems affect his French?
Most likely, I've heard some Francophones say that his cadence is off, that he puts the emphasis on the wrong syllables sometimes, but he already spoke French before it manifested so the effect would be minimal.
It works like this...you have trouble hearing certain tones (for me it's children and some women's voices), you have trouble hearing when there's a lot of background noise (like in room full of people shuffling around and talking amongst themselves), you have trouble with certain accents (for me it's the East European ones, which doesn't go over well with the Ukrainian side of my family).
It's not serious enough that I would consider it a disability and, on the bright side, it makes it easy to tune out my brother's kids when they start whining, but I can certainly see it creating a problem for Dion in his situation. It isn't something that a grown-up would make fun of though, especially just to make some cheap political points.