As longtimedisneylurker said, the attractions will generally remain open until the park closes (unless there is some mechanical difficulty). (Although, for some reason, I think Storybook Canal and Casey Jr sometimes run on their own schedule - I can't say for sure.) The FL rides (at least PP, Snow White, Pinocchio, Carousel, and Mr. Toad) close during fireworks; I can't remember if Alice and Mad Tea Party are running. I think Anna & Elsa also do not meet during fireworks (at least they weren't there on Saturday). The attractions stay closed until the all clear is given. The line for PP starts forming before they re-open FL over by the Mad Hatter Hat Shop (heading towards Mad Tea Party) and then CMs escort the line to Peter Pan before opening the rest of FL.
I do think the lines for some FL rides are shorter at closing (e.g., Snow White, Pinnochio, Mr. Toad, Carousel), but I haven't noticed a major drop in the line for Peter Pan.