So does the ECM control the BCS?

Does a new ECM have to be programed/flashed for the specific vehicle or can I mount just any JY ECM?

Still wondering about the three questions I posted.

1. Why does this trick work?

2. What about that NEW BCS? (it's just sitting there now, not bolted to the BBV, the new BBV did not have the tab to bolt it down)

3. Are there any side affects of doing this?