Yup, going directly to the blue adaptor is the way to do it.
It's all about marketing - using GPH instead of GPM makes the number look bigger. 1 GPM = 60 GPH and thus, 40 GPM = 2400 GPH.
Schedule 40 & other schedules (Schedule 80, 120, etc) are standard pipe ratings. A sch 40 pipe is rated...