I've yet to try Fedora Core 4, but the install time seems too long. Don't remember any Linux install taking that long (with the exception of Gentoo), so I'd think there was something wrong here.
Unfortunately, the installer crashing or otherwise misbehaving is something that's happened to me a few times. Not often at all, but it can be annoying when it does.
Changing the desktop/window manager is often done in the login screen. Maybe Fedora is different..
For finding an easy to use distro, check out Distrowatch.com. While it doesn't directly say so, the top 5 distributions are probably some of the easiest ones to install and use for beginners. It's no coincidence that they're on top.
The best place to look for help and support, if you don't have any friends knowledgable about Linux, is the various forums on the web. The Ubuntu forums are supposed to be a great place to get help, if you use Ubuntu. Ditto for Gentoo (while whether or not the distro is friendly for beginner is certainly debatable, they have some of the best forums on the web).
You can't find an ubiased opinion about what's best of KDE and GNOME, because there is no "best". They're both good, but they're very different.
In short (and I've seen this written several places on the web, and in reviews);
KDE: Windows-like and the King of Configurability. You can configure everything to your needs, and then some.
GNOME: Mac-like and the King of Simplicity. They're aiming for keeping everything as simple as possible (and sometimes they overdo it), with decent defaults.
A Mac User Tries Linux Part 2
A Mac User Tries Linux Part 1