1. Custom CSS would be required for that. Setting a common height for all of them is definitely the more common implementation because it only requires CSS. A common height for a single row or a masonry type would likely require some javascript.
See our guide about creating custom CSS here.
https://wpgeodirectory.com/docs/customizing-your-style/
2. City pages are created automatically. There is one for each CPT and one for each CPT+ Category, and one for the location using the location page template. Use the settings in GD – Settings – General – Pages to find your location page
3. Inside the pages settings you can see the default content. gd_loop_paging will add page numbers. GD Loop elements should only be used on the archive pages. If you are on a WP Page then use the shortcode builder to create a GD Listings shortcode with paging.
https://wpgeodirectory.com/docs-v2/geodirectory/shortcode-builder/
Read more about templates here:
https://wpgeodirectory.com/docs-v2/templates/
4. GD Loop is only for the archive templates. See #3 above.