There is no charge to get to Cirque, which is not in Pleasure Island. It is in Downtown Disney West-Side and you actually have to walk back toward Downtown Disney to get to Pleasure Island; also, I believe they have ended the entry charge to PI. The 6 o'clock show will end about 7:40 to 7:50; it can vary depending on actual start time which can vary by 5 or 10 minutes. It is a non-stop show (no breaks, so go before you enter). For Rainforest, you have to walk a long way from Cirque and thus 8:30 is the safer time. When you say fireworks, I am not sure which ones you are referring to since Downtown Disney area does not have them and you will be about 4 miles away from any. To get back to a park--MK for fireworks, Epcot for Illuminations (with fireworks), or MGM for Fantasmic (with some fireworks)-- by bus after Cirque can easily take an hour. To get back to AKL (Boma) by bus can take 25 to 40 minutes depending on how long you have to wait for a bus; by car 20 minutes. Also note, particularly for Rainforest Cafe, that wait time in that place, even if you have a ressie, can be long.