Hardware and performance

> Once I add the space, will moodle automatically point to it or will I have to change something in config?

Handling disks is the job of the operating system. Since yours is Unix, you have to:
- "mount" the drive on to your file system (means also changing some configuration files like /etc/fstab)
- restart the machine to make sure it stays mounted after a power failure
- shift whatever files from the old place to new, edit config.php of Moodle and finally
- restart the services Apache, MySQL even mail (if outgoing mail was also handled by the same server).