META is an extension to ones Instructor Rating (some would say a re-issue, but it is actually the removal of the "single engine" limitation).
Check And Training is totally different, for one you need to look at the particular approval issued to the pilot to see exactly what they are entitled too, C&T approval does not automatically allow endorsements.
You do not require an Instructor Rating to have a C&T approval.
With appropriate experience an Instructor Rating makes the C&T approval process considerably easier.