This means that you cant log in or access your character until the maintenance window is over.Basic documentation and requirements are posted here on TechNet.

Grommets are metal pieces that can accept a tear on one side.In order to fix the damage, you'll have to maneuver the tears so they connect the spool of thread piece with the tie-off piece.

And before you ask: It does not mean less content.As of this writing, N-1 for deferred channel is 6965.2117 and latest version is 7369.2118.