Also take a look at 9front's FQA, glossary, and readme.
Because it's a tangible proof of thesis behind that same project.
Because 9front gives Plan 9 usability, compatibility, and stability.
There is a list here.
There is no official method for that. You should use the method that is the most suitable for you, which is one that lets you learn the most, with the least effort and time. If you don't know where to start, I suggest reading 9front's FQA (except the chapter about hardware, unless you're interested).
If you're using GRUB 2, good news! You can find the guide in grub.md.