Multifunction control unit, analog to CAN

Hello everyone,
First of all, as a new user of this forum, I'd like to say hello and briefly explain why I'm here.
In my garage, I have a Golf 2 that is fully functional and was completely restored during a 16-month project that concluded in May 2007.
For the engine, I chose a Jetta 5 TFSI engine, which was completely installed with an onboard network control unit, a gateway, an engine control unit, a combination instrument, fuel pump control units and the corresponding fuel pump, the appropriate throttle pedal, an ignition key with a lock and a reading coil, and all the necessary sensors.
'All control units that are missing have been de-registered in the gateway. However, the existing control units are still searching for these devices, cannot find them, and are generating error codes. For example, in the MSG, there are errors related to the ABS and the speedometer signal. In the instrument cluster, I currently still see that the rear right door and the tailgate are open... and, of course, the speedometer (km/h display) is not working.' The switch to a two-door configuration can only be done through the comfort control module, where I can select between a two-door or four-door setting.
For diagnostics, I use the full version of V*G-Com with the appropriate CAN-enabled diagnostic cable. A friend of mine is offering this to me; he bought it for his workshop.
With this, I was able to make all the necessary settings, configurations, and clear any errors (to the extent that was possible).
Currently, I'm using a motorcycle speedometer as my speedometer. By the way, the TÜV inspector also approved it, and the approval has been granted for the vehicle with all the modifications.
I've driven the car for about 3000 km now, and I'm at least satisfied with its mechanical performance. Now, of course, the electronic issues still need to be resolved.
And for that reason, I now need a CAN bus controller that will transmit various signals onto the CAN bus.
This includes:
- Speed sensor, where I could use the Hall sensor from the motorcycle's speedometer as a source... but it would be even better to use the wheel sensor from the ABS system of a Volkswagen Golf 3.
-Switched ground for illuminating the ABS warning light on the instrument cluster.
- Control lights for high beam, left turn signal, right turn signal, and MFA (Multi-Function Display) controls, all operated via the built-in Golf 4 switches.
- Door open (left), door open (right), hood open, and trunk open, all controlled via mass-switched contacts.

I would also need a way to control the motor speed. It should be a TTL signal to control the Golf 4 Climatronic.

I am quite a novice in this field, but I would like to delve deeper into it (after all, one never stops learning ).

Is it possible to realize such a project using the software offered here and the Canhack CANUSB adapter?
I need to first listen to the CAN bus on a 'complete' vehicle to figure out which message corresponds to which function, right? That's what the adapter is designed for.
The actual control unit is supposed to operate autonomously, so there shouldn't be a computer in the trunk .
Is this CANUSB adapter also usable as a diagnostic tool, like diesel mechanics use with VAG-COM?
Okay... for now, let's just stick to the written text. I would really appreciate some answers .

Best regards.
Mario.