AC power tracks, PCB design guides
You should use a PCB trace width calculator, I think you will find for 10-15A 40mil is a bit undersized. 10A on a 1 inch trace with 1oz/in copper will see a 100C temperature rise.

https://www.4pcb.com/trace-width-calculator.html

Also depending on what and where this is being used, your distance between high voltage traces to low voltage or isolated signals is defined by regulatory bodies. In the US that is UL, in Europe that is CE.

Layers:

Yes it makes sense to put them on separate payers for better separation.