The shutdown functionality depends on the power-saving
functionality. If your machine doesn't power off on halt check
whether apmd or acpid are running. If the machine is an
SMP-box power-off won't work, because in an SMP environment
the kernel will disable apm.
The permission(s) to shutdown/reboot the machine are
best granted by editing the file /etc/sudoer and give
permissions to run those two to everyone.
Now only root can access the mounted partitions. I
would like my users to almost have the same permission as
root how do I do that? (not by typing su in the prompt everytime)
I don't quite understand what you mean here ... are you
trying to get access to a FAT or NTFS partition? Otherwise
what you're saying wouldn't make any sense.