For the Compare Listings button, how do I place it in the same position as in the demo?
By moving the shortcode or block to below the images block or shortcode.
Also, I’m not seeing the neighborhood show for any of the places. In fact, all of them have Honolulu for some reason.
A neighborhood will only be added if you update the address of the listing.
How do you just show “Category” as a widget and not the tags with it?
Either remove the tags from the listing, or hide with CSS.
.geodir-tags {display: none;}
Review https://wpgeodirectory.com/docs/customizing-your-style/ for more CSS tweaks.
How do you get the horizontal rule and subheaders to appear between each widget?
Add CSS, for example
.sd .sidebar .widget {border-bottom: 1px solid #ccc;}
Review https://wpgeodirectory.com/docs/customizing-your-style/ for more CSS tweaks, you really need to have a go at this yourself.
Have a look at https://wpgeodirectory.com/support-policy/ and we will only give customization advice if at least you try yourself.