Using two pumps is OK because you have a pretty large loop here. When you connect them in series it will provide a better pressure while in a parallel connection it would provide a better flow rate. The position of each pump (in a serial setup) does not really matter. One pump should be connected to the reservoir since it helps to fill up the system easily.

The radiator setup will provide more than enough cooling performance.

You can connect everything to the aquaero. The aquastream pumps use the same aquabus ID number by default so you have to change it for one pump. This can be done in the system tab of the aquasuite when the pump is connected via USB. To connect everything you will also need some y-adapters for the aquabus port.

The aquaero can handle every flow sensor and temperature sensor that we offer. If you get a flow sensor with USB you also have to change the aquabus ID number because the aqualis with fill level sensor will use the same by default. These devices use the same controller board.

If the aquaero 6 is a part of your order you can go with the PWM controlled fans from Corsair. If you already own the aquaero it might depend on its age if this would be useful. The Corsair fans have some strange PWM handling and older revisions can only control about five of them per port. If you connect more fans the adjustable range will become smaller with each fan till all of them will run at full speed and can not be controlled anymore. With current devices this problem is gone. We did some small changes on the board to allow more of these Corsair fans to be controllable.

For the parallel or serial flow I only wanted to show the difference and not to recommend a specific one. In the end it will be up to your how you use them.

Your question if pressure or flow is better can not be really answered. It is like I would ask you if for a flash light the brightness or its runtime is more important - of course you would like to have both Using a serial setup is more common and also easier to handle.

About the radiators: you can ask ten people and I promise you will get ten different answers here because everyone has a different point of view. It still say it will be more than enough cooling performance. In theory every component has its own radiator in your setup.

It is definitely wrong that this CPU will have a higher power consumption than three GTX 980 cards. That would be something about 450W... I guess you can tell for yourself how unrealistic that is.