Not quite that many…
Question 7: What are two notable differences in the behaviour of Plums between Rayman 2 and 3?
Well, other than Polokus (obviously) and Ly (who tells Rayman about them), you can assume the Guardians of the Masks know (the PSX version at least has dialog on the subject between them and Rayman). Also, Razorbeard knows. As for Razorbeard's lackey - it is not clear from context whether had known of them before, or only when Razorbeard mentioned them ("He must not get the 4 Masks!"), which was after Rayman.Question 8: What characters in Rayman 2 appear to know about the Four Masks before Rayman himself does?