How can the ablution parts (face, head, hands, and feet) be generally and thoroughly washed without omitting any part, and is it obligatory to wipe the inside of the ear cavities?

The correct description of ablution (Wudu') involves thoroughly washing the ablution organs with water. It is sufficient to take a handful of water and pour it over the entire limb three times for the Sunnah (definition), or once for sufficiency, ensuring that the water reaches the entire limb. As for wiping the head, it should be done from the front to the back and then returned. There is no need to ensure that every strand of hair is wet, as wiping is based on ease. Wiping the ears is a Sunnah, and it is done by inserting the index fingers into the ear canals and wiping the back of the ears with the thumbs. There is no need to wipe the cartilages of the ear due to the hardship involved.