It's an annoying way for automakers to make more money from us, forcing buyers to go for a higher trim and additional options just to get a larger screen. Makes sense from their financial perspective, but an annoyance on ours. One day an 8-inch will be the standard screen size with how far we're advancing constantly in terms of car tech and screen sizes. Never know, one day all cars will be like Tesla with a large touchscreen. In the meantime, I'll be looking into that 8-inch screen.
As for connections, not sure about the arm rest cubby, but there are two USB ports in the center stack around the drive selection dial.