Question reg. Fungi Staff

[cantona2k]

Hi all,
i have a question regarding the Fungi Staff (post nerf).
i never owned one and have ben interested in this quite a while:

how does the effect of the staff work for DRU/ SHM?
- as i understand, it's clickable if equipped
- does is stack with a regen spell (cast)?
- does it stack with e.g. a Fungi Tunic?
- does the Fungi Staff have to STAY equipped after having clicked it? or could i click and switch to another item?
- how long is the duration of the effect?

Thanks a ton for your help !!