Thanks for answering my questions everyone -

when I use yum, is the right way to just say "yum update" to update everything, or does it know what I'm missing?

From the yum manual page (type "man yum" at a command-line terminal to read it; press "Page Up" and "Page Down" to scroll; press "q" to quit):

yum update
If run without any packages, update will update every currently installed package. If one or more packages are specified, Yum will only update the listed packages. While updating packages, yum will ensure that all dependencies are satisfied.

So, "yum update" will update every currently installed package for which an update exists. (It won't install any packages you don't already have installed with the "update" command.)

You might want to check out the Unofficial Fedora FAQ and replace your "/etc/yum.conf" (YUM configuration file) with his.