How to create blog posts quicker using template and dynamic source

I use a theme called Impulse on my webpage and would like to create blog posts with it. I have created new templates for my blog posts. Here are 2 questions I would like to solve.

  1. How do I use those templates to create new blog posts quickly?
  2. I want to insert dynamic source(Current page-main product) like I did for product pages. But it is not available on blog posts page, I can only see “branding” option. (see picture)