Category pages, enable comments, blankslate

Really enjoying the freedom of the blankslate theme by TidyThemes, but fairly new to wordpress and have a couple of questions.

I’m setting up a blog page for a friend that has four main categories: blog, images, ___ of the month, and contact. I’ve set these up as category pages so the person who will eventually own the site simply uploads content, checks the category it belongs in, and the new content will display on that page. This is all working perfectly well for me so far.

Enter comments. I currently have the following appearing beneath every post:
categories: images | content (where ‘images’ is the post’s category type). There is, however, no way currently to enter comments on a blog post, image, etc.

I’ve had no real success with any of the other forum topics on this issue (most of which are 5-6 years old). So is there a way to allow visitors to the site to comment on blog posts and images? If not, how can I restructure the site so that each category still occupies it’s own page (linked form the main nav bar) and allows the site editor to upload content to a specific page?

Thanks,
-Jim