Seriously, a slight crouch will let the canopy go right over. You'll learn to duck after one or two slight scalpings. As for headroom, I'm 6'2" tall and use a thinner seat cushion than the seat on my wifes side.
Yes and no....It depends on how high you like to sit. My wife likes to sit up high so we use two bolsters under her and she has to duck a little until the taller part of the canopy comes forward. I don't care about sitting that high and don't need to duck much.
Regards,
FWIW I've had two 6'3" guys aboard during transition training and they both had to duck until the canopy came forward.