No, distinct nuclei begin to form during the Telophase, and Cytokinesis, the division of the cell's cytoplasm to create two distinct cells, occurs shortly after.
These can happen by fission where a nucleus splits into two parts on absorbing a neutron, or by radioactive decay.
mitosis
yes they are both present in interphase
During prophase, the DNA condenses to form chromosomes and the nuclear membrane dissolves. The nucleolus also dissolves.