Definitely need to define the actual classification you are aiming for, and have a full standard such as 60950 to refer to. One key issue relates to mains isolation, or not, and to settle on the definition of the secondary side circuit, such as if it is grounded or floating.
Wrt the pcb, then try and cut pads to maximise clearance, and use a screen resist layer.
Wrt the pcb, then try and cut pads to maximise clearance, and use a screen resist layer.