What are the boundaries of the white area between the head and the ear? Is it obligatory to wipe the hair hanging from the head onto this area? And what is the ruling on someone who wipes a part of their head, then their ears, then completes the rest of their head?

The white area between the hair and the ear is part of the head over which one wipes. If the hair extends over it, wiping over it is sufficient. The described method for wiping the head is valid, even if it deviates from the Sunnah. The Sunnah involves placing both hands at the front of the head, moving them to the nape of the neck, and then returning them. Wiping the ears should be done after wiping the head; if one wipes them before, it is not counted. However, omitting the wiping of the ears does not affect the validity of the ablution.