CAN IDs for Vehicle Diagnostics

Hi!

I'm glad you exist; finally, someone I can communicate with about CAN .
I have a question (for now ).

I'm building a device based on an ATmega16 and MCP2515 to operate on the CAN bus. During programming, I realized that if I need to communicate between two of my devices, I can set the ID myself. How does this work when communicating with the OBD2 system in a vehicle? How do I configure the ID so there are no conflicts and so that the CAN bus in the vehicle allows messages through using its message filters?
It is supposedly explained in the ISO 15765-(1..4) standard, but it unfortunately costs around $350.

and, because it's so nice chatting with you, I have another question right away .

Could someone briefly explain the steps that must be taken during initialization (up to service 0, PID 0)?

Thank you for any answers, or if these topics have already been discussed, please point me to the relevant information.

Robinsam.