Sorry, some of the formatting was stripped out of my comment. This might make a bit more sense:

How do I get the image (a laptop in the demo theme) to appear at the top-left of a post page, so that people can click it to get back to home?

How did you get the comment count to appear next to the top ‘Write a comment’ button (like on the demo site)?

I see on the demo site beneath each post excerpt you have:

AUTHOR NAME in CATEGORY | WORD COUNT | COMMENT COUNT

The comment count is already there, and I know how to get the word count, but how do you get author name and category to appear?

And on the post page you have (above the headline):

in CATEGORY

How do you do that?