The emulation that Shias do is not a blind emulation. It is, rather, based on vision and wisdom, since everybody is asked to observe the Sharia and act upon its obligations and refrain from what it prohibits; and at the same time, a normal Muslim does not possess the specialized capabilities to know the laws of the religion; it becomes natural for those who are not experts in this field to refer to the jurist who specializes in deriving the rulings of the Sharia after exerting great efforts in order to reach religious conclusions. This process is commonly practiced by normal people all the time, when they refer - in the aspects that require scientific efforts – to those who specialize in the specific fields, like medical doctors and engineers, and they act upon their findings and conclusions.
Yes, it is permissible, but it is prohibited if one of them is not consenting.
The part of the body and clothing that came in contact with urine becomes najis, and whatever comes in contact with the najis body or clothing with transferring dampness also becomes najis. So, if the sweat transfers the wetness from the najis body or clothing to anything else, the latter also becomes najis.
It is sufficient to pour the water, and wiping in not obligatory.