The Culture Fair test is visual in nature, with 4 components that test different aspects of visual reasoning. The Mensa Norway test has a vague similarity to one component of the test, although there are quite significant differences. I scored IQ 133 (SD=15) on the online Mensa Norway test you mention on my first attempt.
Although I am not a mensa member, when I got into primary, my Iq was tested and the result was 138. It was very clear that I was different compared to others by many reasons, one was that I was able to read with three years, or that i basically knew every single european country with its capitol and population when I was four. Mensa online tests [especially Mensa dk and Mensa No] are standardized on a selective biased sample and not on the general population. These are tests that usually only people with an IQ of 105-110 and above are interested to do. The Mensa Norway test is fairly accurate from what I've seen and heard so far, if you scored 140 you should have a fairly good chance at passing a non-verbal Mensa Test. As for studying, I think it's better to go in blind. It provides more accurate results and a more genuine outcome rather than cramming online IQ tests beforehand to train