Okay. On Ubuntu-based Linux distros, the user is NOT running as an administrator (as root) during normal operation. You can temporarily be granted root privileges to perform admin activities, like installing software, but to do so requires entering a password. Nothing can be done to make critical system changes without entering the password. There's no pop-up box that you just click "OK" on -- you have to enter a password to do anything as root.
Root privileges expire within a short time frame (approx. 10 minutes I think), or as soon as you close out the program you were conducting the admin functions in. Then you are back to running as a normal user again.
To run a command in the terminal as root you begin the command with "sudo", then enter your password. For example, if you wanted to install the "Radiotray" program, you would not be able to do it with this command:
Code:
apt-get install radiotray
You would have to precede the command with "sudo" like this:
Code:
sudo apt-get install radiotray
Then, you would have to confirm the action by entering your password when asked -- otherwise the action will fail.
If you want to run a GUI program as root, then you precede the command with "gksu". Here's an example where you open the Leafpad text editor as root:
If your password is known by others, or easily guessed then that's a different problem. Aside from that, admin functions can't be performed without you deliberately allowing them.
Long story short -- you don't need to create a separate user account. It's a good thing to have for other users of the computer that you don't want to give root privileges to, but if it's just you there is no need for that.
With regard to keeping data on a separate partition, I like that idea and do the same thing myself. Makes things a lot easier if you ever need to re-install, upgrade, switch distros, or access the same data from different operating systems.
P.s. Some other Linux distros do things differently. They may indeed have separate root and normal users and not use the "sudo" and "gksu" methods of granting temporary elevated privileges; but that's not the case with LL.