Your first question
The copilot can log PIC time, as long he is a required crew member.
Your second question.
Yes, the supervising pilot must be a CFI. It's all about training here.
A safety pilot on a simulated IFR flight, can not log PIC time, because he is not the sole manipulator of the controls. He is a required crew member, but not a CFI doing training. He/she is not supervising.
An ATP is needed for ... airline work.