Princes of The Apocalypse, but I have more than four players. How do I adjust encounters?

How would you beef up the Princes in PotA for an 8 member party?

How do I keep Princes of the Apocalypse from being purely a dungeon crawl?

Sharktoothed longsword from the Crushing Wave Reaver in Princes of the Apocalypse, usable by PCs?

Princes of tht Apocalypse player turned to stone…