Payrates are all listed on the rates page here on ROVworld. Thats a very good indication.
I doubt you are going to get replies from managers of Companies saying “this is what we offer” which is what your message sounds like you’re after.
If you have an idea as to which company you are interested in, then Im sure people on here can tell you what that company offers in the way of T&Cs and work etc. But if you want someone to list all the companies and all the contracts they offer and all the types of work they do…etc.
I know some companies DO offer guaranteed days (dayrate). The salary ones offer the salary and an offshore allowance for each day offshore, contracts tend to be based on 185 days (getting paid even more for any day worked more than that).
Generally if you join a company you cannot say “I will only work in North Sea, I wont work W Africa; I wil only work on boats, I wont do Drill Support” etc. as even in these busy times they cannot take people on on that basis. If you want to do that, you need to go Agency.
Get a job with a UK based office of whatever company, you will then be paid North Sea rates no matter where they send you in the world.