Oracle Linux is Open-Source software under the terms of the GNU General Public License (GPL). It is free to download and distribute, including patches and updates, and you can use the software free of charge, even for running your business. Oracle Linux technical support and access to Oracle service infrastructures and additional services, such as Ksplice technology, are available through a paid subscription to the Oracle Unbreakable Network (ULN).
You might want to check the following link, which also provides info about ULN access.
The up2date utility under Under Oracle Linux 5 is a similar tool like yum, but meant for users with a paid support subscription. In case you messed up your default yum repository configuration, you can check and empty the /etc/yum.repos.d directory and install the system default following the instructions at http://public-yum.oracle.com.