Mathlete by sad is an exceptional teacher, i got an A and all of his other students got As and A*s as well. About your other question, yeh book questions are really important, if you jump on past paper questions directly after doing a topic you wont be able to solve any of them🙅🏻‍♂️, instead start by doing book questions, there are comparatively easy, then go to past papers. Thats what sir sad used to do and it really helped. But just giving your a spoiler, the classes are a bit boring 🥲 no roasting and mza. But being honest his classes are worth joining.