Withered

I have few questions about withered since it seems so important for chaos occultist

1) Does each stack of withered have its independent duration, meaning that if you inflict 1 stack per second and it lasts 5 seconds, by the time you inflict the 6th stack would the first expire?

And as a followup, if refreshing the debuff resets the duration of all stacks, does it mean that if i inflict 7 stacks with withering step, which last 3 seconds, and then the occultist withering presence ticks, does it extend those 7 stacks to 15 sec?

2) What is the radius of "nearby" for Withering Presence?

1) Yes, each stack is independent. New stacks do not refresh old ones.

2) Ascendancy Nearby is 60 units.