How can I keep my branch up to date with master with git?
Assuming you're fine with taking all of the changes in master, what you want is:
git checkout <my branch>
to switch the working tree to your branch; then:
git merge master
to merge all the changes in master with yours.
If your branch is local only and hasn't been pushed to the server, use
git rebase master
Otherwise, use
git merge master
You can use the cherry-pick to get the particular bug fix commit(s)
$ git checkout branch
$ git cherry-pick bugfix