Switch ubuntu to edubuntu and etc

You can try the following:
sudo apt-get install edubuntu-desktop
sudo apt-get install kubuntu-desktop
sudo apt-get install lubuntu-desktop
sudo apt-get install xubuntu-desktop

sudo apt-get remove edubuntu-desktop

Just be aware that this will take up a large chunk of your harddrive, and add a ton of extra programs that you probably don't need(most of them are KDE versions of GNOME programs/XFCE programs whatever, like instead of gnome-terminal, it is the konsole I believe, or is it Kterminal, i dunno...).

Apart from that to Switch Between The New Unity Lockscreen And LightDM In Ubuntu 14.04
Firstly install CompizConfig Settings Manager (CCSM):
sudo apt-get install compizconfig-settings-manager
Then open CompizConfig Settings Manager, click on Ubuntu Unity Plugin and on the General tab, under "Lockscreen", you can select to use Unity, LightDM or no lockscreen:
That's it - there's no need to restart the system or log out, the settings should be applied instantly.

You can switch between desktop environments by logging out, and choosing which environment with a selection box in one of the corners of the screen.

Once you are done playing around with the other environments, go into synaptic and get rid of the kubuntu-desktop and all others you got, but this won't get rid of any programs that were installed along side it. For that check out this site...
http://www.psychocats.net/ubuntu/puregnome

Transform to MacBuntu
http://www.noobslab.com/2014/04/macbuntu-1404-pack-is-released.html