The default prompt comes from the PS1 environment variable. You could do set this in this way:
The PS1 is an environment variable. This is a temporary fix. If you want to change it permanently, you need to (as root) open /etc/profile and find the part of this shell program that defines PS1. I don't recommend this for newer users. You can paste this code into a .txt file and put in an easily accessible directory and just run it whenever you want to use this prompt. This is how I do it. I simply type:
chmod u+x /home/john/shellPrompt
because that's what I named the thing. (note once you set permission will chmod it will stay that way until you change it.
Up there in the line that starts with "PS1", is a "\u" for user, "@" which is a string, "\w" working directory, "\h" for hostname. You can leave the h out if you want or add "\t", "\d" date and time. The "\" is nessecary as an escape character. If you don't put the \ in there your prompt will look like this
Nice huh? I learned this the hard way so you won't have to.
As to the SU question, you can edit any file that you have permission to, unless you have the root password, then you can edit any file on the machine!
I do use "sudo" occasionally, but SU is better because you don't have to type "sudo" every time you want permission, there is no limit to SU's permission.
If I want to edit a file in a graphical text editor I type
sudo gedit fileName
but I generally use vi for root editing.
As for the SSH question: No. If the connection times out, the client will have to log in again. It's not that much of a task, so I never complained about it. Remember to always save your work. Save it early, and often.
Hope that helps.