aerobat77, re headwind speed addition. What you state is ‘texturaly’ correct, but operationally of little value for maintaining the required (assumed) level of safety.
If you base the landing performance on the reported head wind, i.e.100% wind, then adding 50% of that wind speed to Vref, results in the aircraft having a higher groundspeed than assumed in the landing calculation. This requires more landing distance, which against a planned full-wind distance represents a reduced margin of safety.
Landing distance calculations should be adjusted to account for the higher Vref.
The UK AIP / AIC has a useful reference:
Landing performance of large transport aeroplanes.
So too
AC 91-71 Runway Overrun Prevention.