From your description, I assume that you did not commit any changes yet – is that correct?
If yes, here’s your answers:
How to prevent direct edits to master
You would need to set that in your editor, but that will probably be difficult. Displaying your current branch in your prompt and your editor helps a lot.
How to move the changes into a new branch new-working-branch and then discard working-branch
git checkout -b new-working-branch
git add …
git commit -m "mycommit"
As you didn’t commit anything to master yet, you don’t need to change anything on master. You can now discard your working-branch if you feel like it.
How to move the changes over to working-branch
git checkout -b temp-branch
git add …
git commit -m "mycommit"
git rebase --onto working-branch master
git checkout working-branch
git reset --hard temp-branch
git branch -d temp-branch
If your changes don’t conflict with any changes that are on master, but not in working-branch, this can be done a lot simpler:
git stash
git checkout working-branch
git stash pop