Hi csoweb,
1/ To resolve the issue with the slide, you can download the gk_photo_2.zip file in the attachment and add this folder to the modules\mod_image_show_gk4\styles.
Then from your back-end setting panel, go to Content > site Module > Image Show GK4, in the Basic tabs, you can select the gk_photo_2 in the Module Style section.
2/ To get the alt content to show when slides are collapsed, you can download the script.zip file:
and add this file to the \modules\mod_image_show_gk4\admin folder
NOTE: You should back up the file before override.