All you have to do is remove the new kernel which is pretty easy via rpm.
First, find the exact name of the kernel you want to remove with the command:
rpm -qa | grep kernel
This will list all packages installed with the name kernel. Find the one in the list that you don't like then remove it with:
rpm -ev kernel-version
The kernel should be gone and will not appear in your bootloader menu.
However, I recommend keeping up to date with latest kernels. Sometimes when you update kernels, you have to reconfigure somethings. For example, I can tell you right away that in order to get ntfs support back, go to linux-ntfs.sourceforge.net
and look for the rpm specific to the kernel version and install it. I do that ever time there's a kernel update.
As far as your network and sound goes, did you have to do something after you initially installed FC to get them working? You may have to do it again.
Just some suggestions...