You only have to remove the the y pipe from the upper plenum and if you're careful you can reuse that seal if it's semi new. That 1 maybe metal if you're lucky.
Yes. You leave the earl in it.
Do not remove the cams...., unless you absolutely have to and if you do use something like some white out to mark something so you can put it back in just so.
Shims are about as big around as a nickel. They can very in thickness.
And before you start asking for the future. You will not want to attempt a valve job. There's like 100 billion parts
