Not sure I agree with the previous remarks - it's surprising to see any counting questions in quant these days, irrespective of how well you're doing. Probability does come up, but sparingly (once per exam, I'd say, about as often as standard deviation) - and the probability questions tend to be a little on the hard side, even if you're familiar with the concepts.

As dangerous as it seems, I generally tell students to ignore counting and probability unless they're aiming for a Q49 or higher (for which these days you can't afford to miss more than a few questions). Counting and probability tends to be something most students haven't ever seen, so there aren't even any foggy memories to draw on, and it requires at least as much work as do arithmetic and algebra to answer the harder questions. Arithmetic and algebra, however, are worth the study, as I'd imagine at least 70% of your questions will involve them in some way.