shaders – Unity Custom Deffered Shading

i was trying to understand Unity deferred shading in the documentation, and now i have many questions.

So far the idea is to have one or multiple “shaders” that all draw into “Gbuffers” which are SV_TARGET0 to SV_TARGET3, so its 4 in total.(Are there more depending on the gpu?)

Whats happens after this stage, once its drawn, something has to combine those layers to get a shaded picture.

Is it required to create a custom post-processing shader and force the camera/s to use that specific shader to combine the textures?

It really is confusing at the beginning to be honest, same with urp which is all over the place.