Okay, firstly, how come you were editing xorg.conf to setup sound? Lesson 1: X.org doesn't have anything to do with sound. Lesson 2: Once you have a working xorg.conf consider yourself blessed, don't try and change it
You'll need to rerun xorgconfig and remember that values you used the first time. That's why your monitor is going into standby. You can add users with the useradd command. Read the man page or search for "add user in linux" for some info how to do it, it's very simple but the groups you need to put the user in vary between distrobutions.
In linux, your CDROM is a device, the whole concept is very different from Windows. You'll need to create a directory (most distrobutions do that for you, it's /mnt/cd) and then mount the CDROM device to that mountpoint. Make sense? If not read the man page for mount or Google it, it's pretty simple once you get your head around it. So once you have your mountpoint (/mnt/cd) created, mount the CDROM there like this:
mount -t iso9660 /dev/cdroms/cdrom0 /mnt/cd
And then you'l have access to your files. If you want to remove the CD you'll need to unmount the device (umount command) before it'll let you eject the CD. If you want all this done automagically for you, Google for programs like ivman, automount or if you feel like patching your kernel, supermount is quite good as well.
As for compiling programs, you'll need all the development tools installed such as GCC, make, autoconf, the list is a mile long. Your distrobution will come with all of them but not necessarily installed by default, if you told us what distro you were using we could tell you how to install them. Generic instructions are just crack open whatever program you use to install software and installl everything in the Development category.
Hope that helped