Re: Some questions
Typically the BIOS will have a setting for the boot device order. There are some differences between different motherboards, but usually you can have up to three different boot devices and you can set the order that you want your computer to try to boot from them. For example 1st boot priority might be set to CD/DVD with the second boot device set as a hard disk drive. I usually leave the third boot device disabled. When the BIOS is configured this way the computer will attempt to boot from the CD/DVD drive first. If there isn't anything to boot from in the CD/DVD, then the computer tries the second device, which in my example is the hard disk drive.
So, let's say you install an operating system on your new computer build with the boot order set like I described above. Your computer would boot off the CD/DVD allowing you to install the OS onto the hard disk drive. When you are done installing the OS you would take out your installation CD or DVD and when you start up the computer it would boot from the hard disk after not being able to boot from the CD/DVD drive.
After the operating system is installed, many people will reconfigure the BIOS so that the hard disk drive is the first boot device, in order to speed up the boot process a little.
As for how you access the recovery console, it really depend upon which operating system you are talking about, Windows, Linux, Unix, etc.