I would like to ask some questions to Aeronautical engineers for a research paper for my teacher.

Hi Ortega, thank you for the great questions.  I am excited to know more about the final research paper.  So lets see if I can help..."how many year of engineering does one need for airplane engineering?" A typical engineering degree can be obtained from a traditional four year college or university.  However, due to the amount of math courses along with engineering and science related core classes needed to complete an engineering degree, it may take an engineering student up to an extra year or so to complete a full engineering degree program.  So it may take a student somewhere around five years to complete.   

"Where are the engines located?" The engine locations are mainly based on the mission profile or the purpose of the aircraft.  For example, a business jet may have a typical location of engines being located behind the wing.  This serves the purpose of "pushing" the aircraft, whereas, a commercial such as a 737 would have engines mounted below wings.  The mission profile is less concerned with speed and more focused for efficiency and comfort. 

"Do aeronautical engineers only fix planes?" No, aeronautics refers to the science of aircraft in air.  The term aircraft includes airplanes, rockets, missiles, etc.

"Is it dangerous?" Working with machines and new technology can be dangerous, but good safety measures and support is of the highest priority in the aerospace industry.

"Is it 24/7 worth of fixing planes?" Normally, engineers have a set schedule they work to depending on the program.  It is not 24/7 everyday, but depending on your company and position, there may be some efforts that require 24/7 engineering support for a short period of time.

"What knowledge of planes should I know?" Most jobs will have some on-the job-training.  However, it is great to have knowledge of flight controls of an aircraft: ailerons, flaps, and some systems such as hydraulics and avionics is a major plus. 

"How much does an engineer get paid?" Depends but typical 60k +