[Theme Horse Support Team]

Hi MDMAMGMT,
Ok sure you can work editing the content-extension.php file but if you update to our latest version then all your customization code will be lost. So we recommend you to make the child theme and edit the code on the child theme as i have mentioned before.
Yes you make one page and assign that page for blog full content display template.
Yes for the index page you need to select from dashboard->reading->static front page.
Page post : you full content page name
Thank you