RH Esnterprise Edition is not free. RH has discontinued free Linux distributions, except Fedora (
http://www.redhat.com/fedora/), which is not officially supported by Red Hat or IBM. However, I currently run RH9, which is not supported by IBM, and it works fine, alhtough I had to jump through some hoops to get it to install (search this forum for details on installing DB2 V8 on RH9).
If you buy Red Hat Enterprise Linux (RHEL) 3, you will be able to update the OS to the kernel version you want from the RH website.
I don't know about Red Hat Enterprise Linux (RHEL) 3, but RH9 did not come with korn shell (bash shell only).
When I say GUI install, I mean the DB2 install, which can be done with a script supplied by DB2 or with a GUI program installed with DB2. The GUI works fine under KDE, assuming you follow the documented workarounds for getting it work under Red Hat Enterprise Linux (RHEL) 3.