Well, the Iceland forum (understandably) isn't too busy.
I don't have any specific information for you regarding student employment here. You could try contacting the International Affairs office at RU (en.ru.is/services/international-office/). They could probably answer your questions or at least refer you to a source that can.
If you have specific questions about expenses here, look around some of the other posts to this forum. There has recently been a fair amount of activity on housing prices, cost of groceries, etc. Obviously no one here knows exactly what your standard of living requires, so we can't really answer that question. If you have specific questions that you don't see the answers to on the forum, feel free to ask, and you'll probably get a better response.