- is there any way one could use serial or USB MIDI interfaces with this type of board?
You can use serial port to connect to a MIDI device.
- is there any way to attach a real Amiga keyboard to a device like this instead of a PC USB keyboard? It would feel just right to have an actual A2000 keyboard attached.
In fact you need a PC PS/2 keyboard. To use an USB only keyboard you need an additional small interface board which Mike has just finished designing.
It's possible to implement support for real Amiga keyboard but since our human resources are very limited we hoped somebody from the community would do this.