How does one wipe over the turban, and how is the face washed if the turban covers an upper part of it, and is it sufficient to wash only the exposed part given the hardship of removing it?

It is permissible to wipe over the turban during ablution (wudu'), by wiping the top and sides of the turban after wetting the hands with water. As for washing the face during ablution, the entire face must be washed. The boundaries of the face are from the usual hairline down to the chin lengthwise, and from ear to ear crosswise. Therefore, the turban must be moved away from the face to wash whatever part of the face it covers.