Hi Tom19,
I probably don't have the most up to date info, but I have gone thru an aircraft engineering apprenticeship scheme some time ago. The recruitment concept is still similar.
Getting in. Yes, it is competative! People with Year 10 to Engineering Degree qualifications will be gunning for a slot. They will put you thru a aptitude test first. General maths and science stuff. If you get thru, then an interview, basically to see if you are 'a hands-on' & motivated type person. Talk about hobbies / projects you have done and whether you are more electrically or mechanically minded. Engineering is basically split into 2 streams, Avionics or Mechanical.
Once In. If you want a fast track to become an engineer (LAME), get started on CASA Basic Exams, so that when you graduate, you already have most / all of your exams completed. This improves your chances of employment significantly. Also start filling out a CASA aproved Experience book.
Airline LAMEs can earn anywhere from $50K to $150K p.a. depending on the number of type licenses held and shift pattern worked.
There is progression, but you also need to be patient. As a guide, from first year appentice to first LAME license (eg.B737) will take 5 years min. To make it to the top end and be considered an experienced engineer, 10 years.
Best wishes.