re (1), there are actually some movements against this, most notably in the EU where such monopolistic practices are actively targeted
re (2), yes, but there is less variation than you may think
re (2), yes, but there is less variation than you may think
Is there though? Valve timing, fuel injection, emission control, idle. All of these factors are vastly different from vehicle to vehicle and the majority are variable dependant on how other elements of the engine are performing.
A well written piece of software would have those as presets that you could choose from a long long list of makes, models and engine codes.
Personalize the ecu to the car and you'd have an adapter problem left to deal with.
(voltage levels and pinout).