Piggybacking MIDI over USB (with feedback)

So for my next project, I want to use a generic USB/MIDI controller with drum pads on it (akai mpd-18), but I’d like to augment it with an Arduino for additional knobs/switches/encoders etc…

In the end it would be best to have just 1 USB port on the back, so either piggybacking on the existing signal, or having a mini 2to1 usb hub built in.
Is that kind of thing possible?

Then more importantly/complicatedly, would be that I want to add a small LCD display on the MIDI controller, to know what settings I have going on my computer. I would imagine doing that over serial is easy enough, but I don’t know how that works with what’s mentioned above.

Is LCD feedback possible?