You don't need a PhD to understand noise in astronomical images — here's an introduction to the various sources of noise in astrophotography and how to combat them.
Is it possible to settle the PixInsight vs. Photoshop debate once and for all? Yes: Learn both and gain the skills you need to make better astrophotos!
Knowing your astrophotography setup's pixel scale will help you take better pictures. And to determine pixel scale, you first need to know your field of view.