You can change the size of your image in your WP media library, play around with it . It depends on how large you want it. I have some that are as small as 43×32, others average 64×64…it is up to you to tailor how you would like to see them.
I cannot tell by that screenshot what you have for versions, settings etc. We ask that people provide screenshots of their SLP plugin environment (see posting guidelines)
You can change the plugin style under Settings/view. Again, that is something you would want to experiment with until you have a style that works best with your them and your site.
If you need additional CSS or layout tools you can opt for the experience add-on. Here is the doc site with EXP and what you can do with the add-on. As far as the MAP , see panel settings here.
Additional features are available with Experience add-on, such as Full screen map or Do not auto zoom etc. See doc site here. for additional map display info