BIOS Is the program to boot the computer and load the OS Into the computer's RAM.
go into your bios
BIOS
The BIOS. The BIOS provides services to the OS and the OS provides services to the applications.
yes
Hard Drive (Boot from CD) - Tries to boot, loads BIOS, but won't load OS BIOS Battery might be dead - Replace Battery Power supply (if completely dead)
The drive is probably defective. If it is under warranty, see about getting an RMA from the retailer or manufacturer.
No, to my knowledge the BIOS of a computer is not affected by the installation of any Operating System (OS). The BIOS provides some common information to the OS, so the OS does not have to know specific things that may be different from computer to computer, like the type of hard drive for example. The BIOS takes care of how the hard drive is configured so the OS does not need to worry about it.
plug and play
Yes
True
That depends on the tool used to upgrade. Most tools provided by the manufacturer will not allow you to load an older version of the BIOS. A generic Flash utility may allow you to load an older version. Also, most Intel motherboards have a built-in BIOS repair tool that can load a BIOS from a floppy if the main BIOS is corrupted. This can usually be done safely with an older version of the BIOS.