Usually the rear axle. The parking brakes are also the emergency brakes, and if they were on the front, could render the vehicle unsteerable in an accident avoidance maneuver.
Brakes 'grab' because when pressure is applied to the pedal, a device pumps fluid into a system that has a caliper (a squeezing device) that causes brake pads to squeeze the rotor (round, silver disc...
All four brakes should engage at the same time. You probably need to bleed your front brakes. If road conditions are wet or you haven't driven the car in a while, drum brakes sometimes "grab". Many...
Modern disc brakes, whether metallic or ceramic, work best when heated, to a point. One reason disc rotor size has decreased is to allow brake heat to rise quickly. Most work well in the 200'...