It could be the "wear indicators" on the brake pads telling you it is time to replace
brakes create heat when used, this heat is disipated through the metal of the brakes, suspension and wheels
In a car without ABS, if you slam on the brakes, your wheels will lock and your car will skid. ABS prevents the wheels from locking by releasing the brakes if you start to loose traction.
Friction from the road heating the tires and transferring to the wheels and the brakes friction heating the wheel its self and/or the rims.
No. Usually the parking brake is a separate mechanism from the driving brakes, and its usually only found on the rear wheels.
Kinda-sorta. Usually the front brakes come on faster and harder, so at casual driving the rear brakes might not see much use at all. But at hard braking, all wheels will see some brake action.
On cars for the past 80 years ALL wheels have brakes !
it is normal for it to start only with the clutch in as for the brakes they are probably seized and in dire need of service
There are no emergency brakes on the front wheels of vehicles.
It maens the computer is controling the amount of slip at the drive wheels either by applying the brakes or by chenging the power distribution to the wheels. This happens in slippery driving conditions.
4 wheels = 4 brakes
Alloy wheels are also better heat conductors than steel wheels, improving heat dissipation from the brakes, which reduces the chance of brake failure in more demanding driving conditions. http://www.avc-customs.co.uk/
Parking brakes apply generally on rear wheels to control enough sliding of the vehicle.