Ubuntu :: How To Fully Automate A Minecraft Server

I'm trying to fully automate a Minecraft server, and I decided to use Ubuntu 11.04 on this computer. The computer I'm using for it is an old computer (it's the old family PC, it's about 5 years old (and running amazingly now that I've formatted the hard drive (compared to how it used to run))) so it won't run the Unix environment (or something like that) and runs the Gnome environment instead.

Anyways; the server auto-starts when my computer turns on (my computer also automatically turns on). Now all I need to do is have my computer auto-shutdown at 12:00AM as well as enter the command "stop" into the running terminal. I plan to later add more commands (such as automatically welcoming people to the server when they connect, but that's not important right now and I'll likely be able to figure out if I can get this working).

This is the command I'm using to shutdown the computer:

sudo shutdown -P 24:00

However, it doesn't work. First of all, I need to enter my password, so I need some way to have the shell file enter my password for me whenever the terminal asks for it. Second of all, it just plan doesn't work, even if I enter my password (like, the countdown doesn't appear). As for entering commands into the terminal, the only way I can think of is:echo "stop" But the problem is that doesn't work because it wont enter into the running terminal (and I don't know how to do that).