On a 3 degree slope, if you have a strong HW but use the same airspeed, the groundspeed will be lower, therefore required vertical speed lower (approx 3 time G/S?) so there will be a slightly higher nose attitude. If you are a bus driver you can watch the "ground speed mini" function add lots of airspeed in a strong headwind and see the lower nose attitude. However i do not understand how this would affect the cut off angle being talked about significantly as a one or two degree pitch change would not obscure the view of the runway. eg when landing with flap 3 instead of full on an A320, the pitch attitude is about 5 degrees instead of 2.5 but does not affect the view of the runway threshold?
Also no knowledge of what to do with a gusting tailwind other than land the other way.