The Southern Isles are in the location that The Pirates Isles are in vanilla DnD, I just thought the original name was lame. I have used some of the original lore for some of the islands, but mostly it's my own stuff. That means the surrounding powers are Sembia, Turmish, These, Aglarond, etc. Yo be honest I've not put a lot of research into those. The Isles attract a sorts of folk from all sorts of places.
The Southern Islands Company are a proxy for the Turmish government, and it is them who patrol the islands looking for pirates.
The most famous pirate hunter is probably Commadore Roger Todgeson. He has a long standing enmity with Captain Verse, a pirate captain who has the lofty goal of ousting the Company and starting a pirate republic. Currently he is on his way to Thatch, a town in the Western region, and the place most newcomers to the Isles make landfall The party are also on their way there. Captain Verse feels it is time to try and liberate the town and has asked the party to come to his aid. The Company sense unrest is afoot and have call s Commadore Todgeson to help sure up their forces. The party and their crew, along with Verse and his own crew, will try to take the town before he arrives, and then defend it on e he does.
The last pirate to be caught and killed... hm... I'll say that would be Captain Jack Chaffinch. He was taking a prize out East when he ran into Todgeson's ship. They fought valiantly but were overwhelmed and when Todgeson arrives at Thatch he'll hang him up in the Harbour as a warning nitnto resist him. Chaffinch's ship sails with Todgeson, having been captured. Could they take the ship back ? Apparently he'd managed to take a Theskian treasure galleon before being caught himself. Could be the gold is still in its hold, just waiting for greedy pirates hands to reclaim it!
In terms if crew positions, mine might not be the most realistic but are designed to give the players interesting roles and ways to effect things.
The Captain - gives orders, makes in-the-moment tactical decisions
The Quartermaster - in charge of the crew and keeping them fed and watered, in charge of rum rationing as well
Lookout - doesn't seem like much, but if you put a PC with high perception in that role, you'll spot stiff better
Cook - has a big effect on the morale of the crew
Shantyman - perfect role for a bard. Also has a big effect on morale and can inspire great feats from the crew with performance checks.
Bosun - in charge of maintaining the ship, when repairs are needed, etc.
There is a pirate code that they are expected to follow. Captain Verse insisted on this when he helped the players take their ship. Its quite long but the big points are:
Generally the pirates work together, and if there was a local pirate leader that would be Captain Verse. Some go rogue or shun the pirate code, like the BBEG pirate captain Blackfin, who's crew are mostly undead and who has no allegiance other than to his Demon Lord, Orcus. Verse has done a great job of uniting at least rhe pirates in the Western regions of the Isles, and hopes to lead an uprising against The Company and start a pirate republic.