When to automate tests in a CI/CD workflow?

Trying to wrap my mind around a CI/CD workflow.

I know some of this is subjective but what I'm trying to gather is how some of these concepts fit together?

This is my current understanding. Please poke holes in it:

1. Developer works off a feature branch
2. Developer runs test locally and creates a Pull Request
3. Reviewer pulls down feature branch and runs it manually
4. Review approves PR and merges into develop
5. Automated tests are ran
6. Dev is deployed
7. When ready to release, a PR is created for Prod
8. dev is merged to master and automated tests are run again
9. master is deployed to production env

So my questions are:

1. Would you generally create a hook to run automated tests before the developer even pushes their feature branch to remote? Or is running automated tests at every step of the way overkill?
2. On the initial pull request, would the reviewer generally review the changes locally or would you deploy it to a server first?