3 - You have some file in your project /theme which need to be removed/deleted .ds_store which is hidden. On your PC/Mac enable Show hidden files, find that file and delete.
2 - ‘COMMENTS’ replace with ‘Comments’ and add CSS selector like
1 - I am not sure 100% about this but probably is following (I will try to explain):
In all my themes I always have the default logo and that default logo is always set by default when you install the theme (of course, there is an option in Customizer to remove/set your own logo).
But when you don’t have this default logo (which was a case with my Volos theme - it is designed without logo), by default I show the site title and description and I have a option to hide this text in Customizer.
You can see from my “installation video” here - https://www.youtube.com/watch?v=aq0GDBJgJSo&feature=youtu.be&t=170 - by default (in top left corner, bellow the menu burger) I have a Site Title (Volos) and Site description there but after that I am hiding that because I don’t use that in my demo.
I think, that is what they are asking to change/fix.