Apologies for the delay in response .
This is quite achievable with bit of customiazation in the api itself .
To make first section free : this is already available in theme .you can enable this from course pricing settings .
But this is not available in app right now .
4 options of payment : this is not available in app as well as on site as of now but can be done with the help of customization.
Would take a bit of code and will be time consuming. We will help you out but right now we do not have much time and resources for it due to WordPress 5.0 update with Gutenberg .
Once we are free we will help you out with this .