The instrument cluster will give you a warning, that the vehicle will not start in X amount of miles.
NO as the exhaust fumes can kill you
Yes, without a proper exhaust system in the car carbon monoxide can enter the passenger compartment and kill you.
You will be ticketed.
Your cars motor will explode.
dont do it the police could catch you
No. have exhaust checked/repaired
nothing, just illegal to drive with out it.
It depends where you are. Some places do not mandate it
Cracked Exhaust manafold. This often happens causing fresh air to fool with the O2 sensors.
Some (front wheel drive) cars have a flexible piece of pipe that connects the exhaust manifold to rest of the exhaust system. The length of pipe is designed to allow the engine to rock back and forth on its mounts. Without the flex joint, the movement of the engine would damage the rest of the exhaust system.
Gears.
depends by the vehicle you drive