As reply to several questions, here is a presentation in brief from NMA re: Ships registered in NIS or NOR: https://www.sjofartsdir.no/globalassets/sjofartsdirektoratet/.../nis_2016.pdf
In regards to crewing of the vessels, here is the basics:
The “subsidies” paid to Owners who hire Norwegians on NIS vessels are described here:
There are no requirement for any kind of visa or work permit for somebody on the crew list of a vessel operating in EU or Norwegian waters, only for work on fixed platforms and rigs, nor any special rules or restrictions for Americans.
IOW; If an American is hired to work on a NIS registered ship operating in EU or UK waters, he/she does not need any special permit or visa, or meet any problem with shore leave etc. That is myths that only exists in America. A Seaman’s Book is all that is required as travel document, but most carry a Passport, just in case. For travel within the Schengen area, no passport is needed.
Of course, CoC per STCW, with all necessary additional training relevant for the job, is required to obtain a CeC from the flag state. Which Flag States that accept US CoCs can be found by googling individually, but Norway, UK and most EU nations recognize US creditations, although US does not reciprocate.
What about wages? Well, wages depends on qualifications as well as supply and demand for the category or position the person is hire for. It can be by individual negotiations, or by Collective agreement.
For NOR flag ships, the wages are fixed by Collective agreement between the Seaman’s Unions and the Shipowner;'s association and are the same, regardless of nationality.