New author. WordPress Requirements for Envato Market?

Hi to all!

I am a new author on Envato Market. I have two HTML templates that are sold ( On their basis, I want to develop WordPress themes. But as far as I understand I got into a difficult time for a beginner)))
I want to do everything right, so I turn to the community of authors who already have a great experience.

  1. According to new requirements, how do I start developing a new theme? Maybe recommendations some frameworks to get started?
  2. What pages are required for my theme? What is the approximate files structure in the themes?
  3. Is it necessary to develop all the post formats?
  4. Can I use meta boxes to build a home page? Or use some page builder (Elementor)? Or develop everything based on Gutenberg?
  5. I do not fully understand the definition of optimization for Gutenberg. Do I need to rewrite styles for all standard blocks?
  6. Should I use widgets in the themes if they are not needed?

If briefly, then I am completely confused…
I do not know what technologies to use? What tools to apply? What way to go in the development of the themes?

I would appreciate the advice!