Test updates are those that needs "testing" to ensure that they don't break anything when installed. Once it has enough karma, it is pushed to "Fedora Updates". Some updates CAN break your system and that is why updates-testing is disabled by default. You can enable it, if you so desire.
Since you are asking about desktop - I assume you are using GNOME 3 (gnome-shell). By default, desktop handling is disabled. See this link
for some of the new things in GNOME 3.
If you are looking for alternatives to GNOME shell because of some reason, there is Cinnamon
, amongst the numerous other desktop environments (KDE, XFCE, Fluxbox, etc). Hope this helps. Welcome to the forum. Cheers.