Apple New Orleans wrote:
I've tracked down a replacement from none other than Mr Eric Lee, but he says on some drives I must solder on the BIOS chip from the old board.
b) Which chip is the BIOS chip?
The fact you need to ask this tells me that you should probably not be working on this case on behalf of a client, and the fact you only know this because you were told by Eric Lee confirms it!
In answer to your question, the 'BIOS is actually the EEPROM and is a 8 leg chip found usually at the top left of the PCB, and yes it will need to be transferred. You should consider the initial problem that caused this damage, and be aware of the possibility that other issues may arise.