I'd like the social icons (Facebook like button, etc) to be displayed directly on the screen rather than accessible by clicking on the "arrow" sign. Is this possible? How? (I believe that most users won't realize that they have to click on the arrow to share the picture - to me this is confusing) Many thanks,
You can create custom UI by editing default one, it's specially added as a separate file, so you can fork it.
https://github.com/dimsemenov/PhotoSwipe/blob/master/dist/photoswipe-ui-default.js#L437 (take a look at how zoom or close buttons are added, you can add another buttons the same way)