Maybe this is just a preference, but I would move the screen that is directly in front of you as high as possible in the panel.

I wouldn't use and iPad as my primary instrument either. I have been using an iPad Mini with an AirGizmo panel mount and never had it overheat; I didn't use the cooling port.

Parallax? There is no such thing when using a screen. Parallax for aircraft instruments describes the difference of what you see when viewing a gauge's needle against the dial from different angles. With a screen WYSIWYG.