Dependent Origination and Impermanence in Buddhism

1 question: I just started learning about Buddhism and I read about the 3 marks of existence. When Buddhism speaks about impermanence does impermanence only refer to our experience (the 5 skhandas) or is outisde world phenomena included and considered impermanent. As I understood it impermanence is a key Buddhist principle. How does Buddhism describe time according to this impermanence doctrine and what is impermanence relationship and connection with time. I have seen a few answers here on a similar question/topic but not really this one so I hope I will get a few answers that can help me understand it. 2 question: Is a dependently arising cycle considered happening in a split second or how fast is it considered happening and what is its relationship and connection with time ??