How does a woman whose left hand has been amputated perform ablution (wudu')? And does she wipe over her left shoulder? And is it permissible for her to wash only her right palm if she cannot roll up her sleeve? And does she pray sitting down due to her inability?

If the arm is amputated above the elbow, it is not necessary to wash it during ablution because the site of the obligatory washing is no longer present. The sound arm must be washed up to the elbow if possible; otherwise, wipe over it. If you are unable to wipe, even by hiring someone to assist you, then you must perform tayammum (dry ablution). If you are unable to perform either ablution or tayammum, then pray according to your condition, for Allah does not burden a soul beyond its capacity. If you are unable to stand, there is no harm in praying while sitting.