When merging to a non-feature branch you'd normally use git merge <branch>. You can do better for the sake of easier reverts and help the review process:
git merge --no-ff <branch>
The naive way to update from upstream is git pull but is better to try:
git up
You did a wrong commit but its already pushed. git reset --hard HEAD~3; git push <branch> will work for you, but your folks will shout things in your face. You better use this:
git revert HEAD~3
git push <branch>
More info here