Ship stuff is basically exactly Black Flag so far... which is brilliant of course. iirc I think there's more upgrading and customisation to be done here though. I don't think enemy ship variety will be as good though but we'll see.
Upgrades are done nicer than Origins. So you can still upgrade your gears level if you want to but you also get loads of loot so you'll pretty much always have gear at your level anyway, you only want to upgrade any legendaries/ super good stuff you can find. You can also "engrave" every bit of gear you get which is basically equipping a rune for a percentage stat boost.
Upgrades are done nicer than Origins. So you can still upgrade your gears level if you want to but you also get loads of loot so you'll pretty much always have gear at your level anyway, you only want to upgrade any legendaries/ super good stuff you can find. You can also "engrave" every bit of gear you get which is basically equipping a rune for a percentage stat boost.