Don't listen to me about the airline. I'm still trying to determine if it makes any real difference in skimming. For now, Id say just remove the airtap, use the stock airline and see how it goes. I'm still trying different things and it seems that once broken in and wide open, the nearly 20LPM may be too much anyway.
The wedge pipe is an adjustable outlet type that ER has started to use. You dont need a gate valve if it has it. I would check with the vendor you buy it from and ask if it has it. Premium Aquatics is a great vendor to deal with. You're in Indiana, so even better for you.
Good luck in the big game today!