1. Re: Keeping Dinay Harchaka in public - It's not only a custom by Chassidim; it's mentioned in דרכי תשובה that הירא את דבר השם will behave this way.
2. Re: Having an Ama between the beds during nida is not from the Arizal. It's from other sources. See Tahara K'halacha page רג footnote 70
3. The source in Gemara that an adult shouldn't sleep in the bedroom of a couple even when the wife is Nida is
עירובין ס"ג , ב
4. It was mentioned that when a woman is Nida she is dirty. It should say she is טמאה.