UEFI and Secure Boot – Getting Windows to boot on Windows 8 laptop

Someone asked for some information about UEFI and Secure Boot on newer computers and how that will affect them putting something other than Windows on their computer.

Their main questions were:

What benefit does a normal home user get from UEFI and Secure boot ?
How does the actual signing get done ?
Who gets to do the signing ?  Only Microsoft ?  Some other company ? How much does it cost ?
What do I need if I want to put Linux on my new computer ?