Hasta La Motion!

Hi, I’m Simon and new in the VFX community.
At the moment I’m playing around with some programs and got some questions.

I use Fusion as compositing software, but I use other programs too (3D, compositing, painting, particles).
My question is the following: how do you combine programs? Is it right to render some layers in After Effects and put them together in Fusion with some pictures and perhaps footage rendered in other software?

Second, when I’m rendering 3D, is it better to render every pass (shadow, highlight, depth, reflection … ) separated and put those together in Fusion as well?

Thanks in advance 😀