That pipe unfortunately will not work. the slot should just be long enough for the screen to fit . Also the screen should be roughed up well. For the pump you want 35 gph
for each square inch of screen. Location of the scrubber will depend on your lighting . You need to have the lights perpendicular to the screen. Use regular PVC
cement that you would on any plumbing. As far as the skimmer I'm keeping mine until it stop producing skimmate. The macro algae will die because the scrubber will outcompete it. You can check the last few pages of my build and see all the mistakes I made lol.