Hi Gills !
Thanks for the comment, I appreciate it.
As in for your questions, I mostly use Substance 3D Painter, I usually play around with this method/option called Projection Painting, and sometimes I do manual paint-overs for details and such.
And for the textures, I usually just search up 'texture-name' cc0 texture/material, and most of the times I find what I am looking for, if not I improvise haha.
Although there are good texture sites like TextureHaven/Poly Haven,/textures.com, I don't rely on any specific one—I just use whatever is convenient at the moment.