It might be different this year as it is a Saturday but last year I went on Halloween which was a Friday. We bought express passes as we went the year before and barely saw anything but last year, we only really needed express for Halloween, the Walking Dead and Giggles and Gore, I think it was called, the clown house. Even with express some had decent waits. Otherwise, some of them, the stand by line was 15 minutes or less.
Seeing as you are doing the Stay and Scream, you can easily get 3-4 houses out of the way right away, depending which holding area you go to. Not sure which holding areas let you out where, I should probably look into that as I'm going on the 1st lol. But do that and if the express passes haven't sold out I believe you can buy them during the event, someone correct me if I'm wrong. The passes are quite a bit of money, for Halloween they are $109.99 and I know last year we felt like we wasted the money as we really didn't need it.