The optimum BIOS settings vary by installed hardware, operating system, and intended use of the PC.
In general, you will want to take the factory defaults, and modify them to your needs.
In order to recommend specific settings for your situation, I would need the manuals for the motherboard, video card, and a list of all installed periphials.
There are several articles in the TechRepublic archives that go into detail on the different settings. Search on bios use all lower case letters.
There is also information available at AMI, Award, and Phoenix web sites.
You can also check out www.wimsbios.com
and www.tomshardware.com for details and recomendations.
As to question 2, enableing memory shadowing, and specifying memory addresses and IRQ's for devices is a holdover from MS-DOS. They can be used to correct a few specific device conflicts. But for the most part Windows (XP in particular) ignors manual settings, and dynamically assigns memory and addresses.
Other than shadowing the video bios, there is no performance advantage in enableing shadowing.
In fact, shadowing can reduce performance by using up memory, and confusing windows.
