Finality counters aren't keyword counters, and a finality counter doesn't give any abilities to the permanent it's on. If that permanent loses its abilities and then would go to a graveyard, it will still be exiled instead.

Finality counters work on any permanent, not only creatures. If a permanent with a finality counter on it would be put into a graveyard from the battlefield, exile it instead.

You pay all costs and follow all timing rules for artifact spells cast with the permission granted by Noctis's last ability.

Finality counters don't stop permanents from going to zones other than the graveyard from the battlefield. For example, if a permanent with a finality counter on it would be put into its owner's hand from the battlefield, it does so normally.

Multiple finality counters on a single permanent are redundant.