Kindly note the following.
Though all the things you have mentioned in your mail are to be learned, consider your specific requirements.
a) Instructional design helps you in planning the entire course from start to finish, i.e., from stating the learning objectives to establishing the evaluation process. However, the majority of organizations tend to handle this internally.
b) Content development would be useful if you are starting a module from scratch. Nowadays, with almost everything available on the internet, it is more about logically sequencing sub-modules and related study material.
c) Learning delivery techniques and adult learning principles are essential for course presentation to be more effective, viewed from the dynamics of learning.
Depending on your requirements, you can decide which aspects to focus on. Ideally, you should learn all aspects to become a well-rounded trainer rather than just delivering pre-made modules.
Kind regards,
Dayanand L. Guddin
General Manager - Strategic HR
Endurance Technologies Ltd