halacha - What are the requirements of a men's mikva?

There are many requirements given for a women's mikvah (See Yoreh De'ah siman 201), yet I have not seen much information regarding a men's mikva (to tovel every day before prayers or for Erev Yom Kippur).

What are its minimum requirements?

1. Can one Tovel in a Keili (according to one Shitta in Gemara Brachos one can. Does Halacha/General practice follow that opinion)?


2. Can one Tovel when the filter is on?


3. Is one allowed to tovel in zochelin (moving waters)?


4. Is one allowed to tovel in snow?