Is standing under the shower, without rubbing some body parts (like the neck, armpit, navel, private parts, and anus), sufficient for ghusl? Is rubbing obligatory? What is the ruling on wiping over a wet head in wudu? What is the ruling on the intention for ghusl according to Abu Hanifa?

What is required in a mandatory ghusl (ritual bath) is to ensure water covers the entire body. Rubbing is not obligatory unless there is something preventing water from reaching, such as a convoluted surface. Wudu (ablution) is valid by wiping the head even if it is wet from the ghusl water, and it is not a condition that the wetness of the head be less than the wetness of the hands. Water reaching the navel varies depending on individuals. As for the intention (niyyah) in ghusl, the majority of jurists hold that it is obligatory, while the Hanafis are of the opinion that it is sunnah (recommended). The preponderant view is that of the majority.