You don't need flight tickets and travel insurance when filling out the online application. However, you would need to upload your hotel reservation or invitation letter, photo, bank account statement to show the applicant commitment to return and something to show your income like a paycheck. When you go to the interview, they are going to ask you about the flight tickets and health/travel insurance which I said that I will buy both of these when my visa get approved. When my visa got approved, I bought my flight tickets and health/travel insurance and mailed them along with my RTD. Regarding photo, they have their
requirements.
You can always send them an email if you have any questions and they are not that bad in responding back to you.