RoPieee does not support command mode: you can configure the necessary stuff on it’s webpage. In this case you only need to select the HAT and you’re good to go.
There’s a double row of pins sticking out of the top of the rPi. The hat has a mating set of sockets that slide onto the pins like a daughter card. It then becomes more or less one unit.
The touch display connects to a ribbon connector at the end of the rPi (which is hard to get to with the hat in place, so think through your assembly order). The second part of the touch screen is that it needs 5V. That is easy to get when there is no hat. Hopefully your hat has more pins sticking up that you can steal gnd and 5V from those pins. If you have questions, I’ll be glad to help, as I’ve been through the rPi, hat, and display thing.
EDIT: I just looked at the HAT you are considering and there are pins for 5V and GND on the hat so you should easily be able to steal power for the display when the hat is in place.
Pi2AES itself is powered at 24V, but it includes voltage regulators to provide 5V@3A to the Pi itself and accessories. Pi 2 Design sell a mounting case for the Pi, Pi2AES, and PiTouch with instructions that explain how to assemble and wire everything.