Okay. Following some guidance from Red Hat, I've found out that SELinux can be set to various modes. Running system-config-securitylevel from the terminal (logged in as root) allows the graphical management of SELinux. The manual method is to Edit /etc/selinux/config .
I see that SELinux has a mode, which can either be SELINUX=permissive or SELINUX=enforcing. In the graphical interface there is a checkblock for Enforcing? which I cleared, thus (I think) changing the mode to permissive. According to Red Hat, "This way SELinux will be running under the correct policy, but will let you login if there is a problem such as incorrect file context labeling."
Now, a reboot gives only two or three error messages, and the related services say they are starting. Most everything works. A few things don't, for instance from the graphical interface "Start Here" gives me a window at start-here:/// with three icons, namely "Applications" , "Preferences" , and "System Settings" . Each of these should navigate the window to applications:/// (and so on), but all three report ' "applications:///" is not a valid location. '
I will have to experiment and see what works and what doesn't ; also, whether even lower levels SELinux are preferred for now. Finally, I think I submit a couple of bugzilla reports at Fedora on this whole topic.
If you learn anything further in this area, please continue to post in this thread. Thanks.