1) It is not Jurisprudically Sunnat; it is encouraged.
2) Yes, along with horse-riding and archery.
3) That Aalim is misled.
4) This is not permissible. Haraam. How can any person look at the Satr of a Ghair-Mahram?
5) This Aalim is not well. What happens when water touches these clothing? Would he like for his mother, wife, sister, daughter, etc to be seen in that state?