with pull requests do I need to take that last step? Instead, can I submit a pull request on my branch and then on GitHub apply it to master?
- you should always submit a pull request from a branch that you have push to your GitHub fork.
- You even can rebase that branch on top of master, git push --force that branch to your fork, and your existing pull request will be updated. Automatically
The only merge of your branch to master will take place in the original repo by the main maintainer, should he/she chose to accept your pull request.
See more with couple of tips for pull requests.