Just a few notes, Yea 3x bows are harder to get a shot in because of the arrow spread if one hits them they have a bit of a recovery period which is suckish.
You can't stun him from behind after bucking you off, i've done this numerous times and he just shakes it off immediately. Though granted...
no sadly, as it's still recovering from the mount, When you get thrown off you can do the slowmo shooting and from what i've seen the shots still do critical damage when they make the noise for stunning it
I tend to find it far easier to strafe around the lynel with z-target on and the shoot him in the face with a 3 shot, rarely miss and it means you can mount more often, i then when i dismount start firing into the head for more damage, i think the most arrows i've used on a lynel fight to date...