Yes, BUT RHEL (and most RH based distros,Fedora, etc) do NOT allow any proprietary parts of any kind in them or their own repos. That means that using their repos only, you cannot play most media, you cannot have Nvidia/ATI closed source graphics drivers, Flash, and a lot of other things. This is why third party repos play such an important part in RH based distros. Because all the third party repos cannot seem to agree to play by the same rules (they have gotten MUCH better since the FC4 days) you do have to be careful mixing third party repos.
The OOffice 3 thing is a different issue. RHEL/Centos is a enterprise distro. This means that its number one priority is stability. Generally speaking most of the major packages will be on the same major release number of that package when the distro version is released as when support is dropped for that distro version. RHEL/Centos5.0 was released with OO2.4 and it is highly likely when support drops for RHEL/Centos5.8 (or however high they go, 5.X) the will still only have OO2.4. Now that does not mean that they will not update their version of OO, they do and they have already. What RHEL/Centos does is to apply back patches to the older versions of the software in order to maintain security and add as many features (as possible) to try to keep up with the more current version of that particular package.