Maybe because a higher ranked wind tech will overpower the lower rank fire tech as too much air is send into the fire.Good job.
As for the bonus question.
A fire Technique that can go Short - Long range and an equal or lower Wind Technique that goes Short Range only should decrease the range to Short - Mid, making it a stronger jutsu, but the range will be lowered.
Long Range + Long Range = Long Range
Long Range + Mid Range = Long Range
Long Range + Short Range = Mid Range
Mid Range + Mid Range = Mid Range
Mid Range + Short Range = Mid Range
Short Range + Short Range = Short Range
Care to explain why a Wind technique, of a higher rank then the fire technique used is a bad thing?