Use Blender 4.3 or newer.

Install like any other addon. Drag the .zip right into Blender and hit ok.

This is an Eevee only effect.

The shader has no lag. The lineart component however can be expensive for very large or very complicated surfaces. Play with the quality and spawn density.

Yes, but I'd be careful. Separate out large surfaces (that would spawn millions of lines) and super detailed meshes and see which you can get away with only applying the shader. It's best to build up slowly instead of slapping it onto a scene collection.

Yes. You can use both the shader/lineart or just one if you want. Target objects can be given a transparent bsdf.

Make sure you have a camera object - lineart is spawned only inside the camera's view.

Either subdivide the target objects or increase the quality slider.