I mean I think it's intentional that there's not data on that sort of thing that is collected or made available. There are methods one could use to get a rough estimate; someone elsewhere in the comments suggested taking the reported yearly profit for the company and dividing it by the number of workers. It's not perfect, but it's better than what we've got right now which is just a big ol 'shrug'.
But there is likely someone doing the math, even if they''re just ballparking it and not making it public, because that's how they justify paying everyone's salary. It would not surprise me at all to learn that giant corporations have a pretty accurate accounting of the value created by each employee.
Yeah, so instead of sending down divers with equipment you're hauling hundreds of tons of concrete out of the sea, which means aside from a ship and crew which you'd need anyway you're still going to need specialized equipment (some big honkin' chains and winches at a minimum) and tools and such, and that stuff isn't cheap either. Also they're aiming at a 20 year partial replacement cycle for parts that are going to be submerged in or otherwise exposed to sea water which is notoriously corrosive, some of which will be at fairly high pressure (otherwise the turbines will be less efficient), that seems optimistic at best, even if nothing breaks before the scheduled replacement time, and you certainly can't count on that.