Headache, Cold feet. Coarctation is a constriction somewhere along the path of the aorta. The symptoms largely depend on where the constriction is. You can have high pressure above and normal to low pressure below. These both cause symptoms like headache (from the high blood pressure) and exercise intolerance and pain in the legs along with cold feet (from the low pressure).
Depends on age. The exact location and severity of the obstruction and age of presentation will dictate the symptoms. Disparity in blood pressures between extremeties may be noted, but associated conditions like intracardiac shunts may present with cyanosis. Shortness of breath and heart failure may be presenting symptoms, but infants can't relay those symptoms. Physical exam and echocardiography are key.