this should be normal, i cannot confirm as none of my bulbs are stock, but the more yellow the light the lower the kelvin rating and thus the more light that is produced. safety is more important than looks, since its the high beams you want more light hence you use them. as for the dimming issue not too sure all i know is that with the afs system it not only adjusts the beam left right up down but also the brightness of the lights atumatically depending on how much light the is outside.
also about the xenon high beams. i think what it means is that it also uses the xenon dipped as high beams. cant remember where i read this but the is has 4 high beams, ive been meaning to check this by unplugging the main high beams and seeing if the xenons adjust their beams, its late now so will try this tommorrow night and let you know whether this is true.