Beginner Questions About Shaders and Best Practices

Hello Everyone,

I am totally new to shaders "Scripting / Visual Scripting" and I am amazed by things that can be achieved.

i have few beginner questions about Shaders in Unity:

1) How do you manage multiple shader effects for the same GameObject?
For example: let's say we have a character who has Toon Shader, Outline Shader and disolve Shader. but the Disolve Shader is only used when the player dies. what is the best approach for this use case?

2) what are the best practices and / or tips that someone should keep in mind while creating shaders and when performance is the priority?

3) Is it possible to use shaders as a way to optimize game performance?
Example: create a shader that adds cracks above the assets using the shader properties to maximize the reuse of materials / textures and have a rich environment.