1 Stu's "stretchy ints", make the protocol more extensible by not limiting various fields. look for standardised way of doing this, and name for it.
3 IP/UDP header wrapping, for CAN vs UART why have addresses in the UART packets when CAN can handle that aspect in a physical way. Interoperability with Jean's extender board? New FreeEMS specific firmware for it?
5 Review and possibly remove multiple interface sending scheme. Why send the same shit over two UARTs, if you want to listen with a logger, just tap the ecuoutput line and do so. Keep possibility of exposing the same interface on two different UARTs, how will this work with one buffer?