1) Away from kickstart, how do you evaluate the following way?
2) If that applies, how can we combine with kickstart?
3) How can I set the option of (automatic partitioning all unpartitioned space) in kickstart configration file? to apply it on all pcs?
To be honest, I don't think there is much worth to evaluate. If you have a plain vanilla system, perhaps the upgrade option is feasible. However, why bother? There are such fundamental changes between version 5 and 6 - I would not have much faith in the upgrade process. If this is all just for the purpose of exercise, I'd recommend to perform a supported update path.
I suggest to read standard Installation Guide regarding upgrading and kickstart, which link you can find in my first reply to you. Note the following: In-place upgrades across major releases do not preserve all system settings, services or custom configurations. Consequently, Red Hat strongly recommends fresh installations when upgrading from one major version to another.
What special configuration needs do you have in the student computer lab that requires to perform an unsupported and unattended upgrade? Wouldn't it be more effective to create a master installation and then simply clone the other hard drives? You can create a little script to run on each computer that will do any special host configuration if necessary - and maybe use it even for the next major release. Otherwise if anything strange happens, what are you going to do? Reinstall the system?
If this was a production system or my home system, I would definitely not bother to upgrade and erase the old system, setup and configure everything from scratch and restore only the data where absolutely necessary. I would even reinstall all Oracle Database software and re-evaluate necessary patches and parameters for the new OS. To me this is the only way to know that I have a clean and properly installed system. It is not difficult to gather the configuration of a server and reconfigure a new setup accordingly. You will have to analyze what you are planning to upgrade anyway. And it is usually a good idea to revisit the configuration needs of a system once in a while and clean it up.