The guy at the store told me that I didn't need to use any glue on any of the PVC connections above the bulkhead including the pipe in the top of the bulkhead.
The drain pipe inside my overflow i usually dont glue. But the return pipes I do glue. Except maybe the last piece that shoots the water back into the tank incase i want to rotate it or whatever to adjust flow.
I would glue it. If there's water pressure flowing through it (the returns) it can leak or even burst. For the drains from the tank, that's all gravity-fed, so there's not a lot of pressure on those pipes.
I just cut slits in it(4) and then hammered it and it slowly came out then I cut a few more slits and a few more whacks and it came out. Whew didn't feel like driving to the store. I have been there like five times in two days.