Categories' images

You can either switch the header text off or change the text. To switch it off, simple set 'Header Text' in the main configuration to 'No'.
To change the text, click the 'Language' button in the KISS Advertiser control panel. This will lead you to the language overrides. Then search for the term 'KISS_CONFIG_WELCOMETEXT'. There you can change the text for both English and German (or whatever language is installed). If no 'KISS_CONFIG_WELCOMETEXT' is found, click on the 'New' button and create a new ressource with the key 'KISS_CONFIG_WELCOMETEXT' and the text whatever you want. After saving, the text is changed. You cannot change it in the en-GB.com_ksadvertiser.ini file because all changes in this file would be overwritten with every update.You can update the current version to the PRO version at any time. Existing data will be kept. Only if you uninstall the component, the data will be lost. Updates do not change any existing data.

It looks like a server directory separator issue.

On your screenshot I saw that your server uses two different separators:
The address looks like

http://localhost/root_dir\components\com_ksadvertiser ....

http://localhost/root_dir/components/com_ksadvertiser....

If the images don't show up although they are present, it could be a user rights issue. Please check your image directories on the server, especially the 'image' and 'media' directories. Set them recursively to at least 0755. Make sure that the owner of the directories is the FTP user, NOT the web server.

The second issue (with the icons placeholder) could be a template issue. Some templates overwrite the Joomla and KISS Advertiser javascript routines and cause problems. To avoid that, go to the KISS Advertiser control panel and click the 'Options' button. In the main configuration, look for the setting 'template problems' and set it to 'yes'.