Fail!
AUG is a vi user. Your workaround is an additional keystroke, but vi is all about keystroke efficiency!
Merely touching the mouse (or its surrogate) is something vi enables its users to avoid (a feature, not a bug). Having to invoke a mode change through a soft function key keyboard first in order to access a basic control key is a deal-breaker.
That said, when not traveling, I use a Bluetooth keyboard (and a 30" external monitor) with my MBP. So, if ESC still works from the BT keyboard, I'm probably happy.
It does. Also, once you've pressed the Function Key, the Function Keys don't go away. They'll stay until you select another application or re-press the Function Key. There is no additional keystroke required if the Function keys are already available.