yeah basically replacing or rewiring all the OEM controls and displays (gauges) is a given unless you want to repeat what vitviper did and reverse engineer the entire car CAN bus. which is definitely possible, you can program motec to accept any can spec you want IIRC.
High performance academy has a course on can bus that includes reverse engineering if you want to stop waiting for someone else to do it for you guys 
It's on my list to take.
Aside from that:
You can do cruise control via can keypad (aftermarket ecu controlled). you could also rewire the steering wheel controls to a can transmitter (similar to whats used in can keypads)
I was thinking about the possibility of taking
https://www.demon-tweeks.com/no/summ...system-663360/
and wiring the outputs to the the same can transmitter to talk to ECU.
the Motec c1212 is a really nice looking dash I would probably use to replace the OEM one. because reverse engineering all the CAN for the oem system is honestly too much work.
other things related. a bosch motorsport ABS unit is definitely the way to go, it will output CAN codes you can read in the ECU to do traction control (wheel speed)
also you can disable it via CAN keypad if you want an ABS button.
you can see a lot of that coming together via motec here
definitely way easier to rewire the whole car tho than to integrate with oem can. but i've never reverse engineered a CAN before so I don't actually know how long it will take.
lol