It used Gran-Gran and Artist's Talent to reduce the cost of spells and discard cards, Monument to Endurance to deal damage to opponents and draw additional cards as cards got discarded, and a variety of Lessons for their interactions and card draw
Its also best to use as a Commander since if you cast it from the command zone youre always getting at least one Forest Dryad
If an effect gives Nevinyrral's Disk indestructible or regenerates it, it stays on the battlefield
Let me address the second one first
It hits hard, is easy to crew, draws you cards when your Pirates deal damage, and can even rise from the depths if it takes too many broadsides, provided you have some tapped Pirates lying around
Many players were quick to point out that Negan is a deeply problematic character who committed such deeply heinous acts in the story that I can't repeat them here