If you’re referring to the portfolio page itself (page that shows all of the posts), then I’m not sure if there is an easy way to do this just yet since the portfolio that comes with this theme is pretty basic (which was the intention). It’s basically just like having a Blog but in a portfolio format. If you need something that is a little more complex and offers more features, I would recommend searching WP.org or Codecanyon for a plugin more dedicated to Portfolios.
Other than that, you can still enable comments on the posts individually since they are regular blog posts.