Hi,
If you want to insert an specific picture from a website, and you know its URL, you simply should insert an img tag in the page’s content, for example, if the URL to the image is:
https://www.sitexwz.com/images/dog.jpg
The tag to insert would be:
<img src="https://www.sitexwz.com/images/dog.jpg" />
About your first question. Our plugin does not insert a shortcode, it inserts the code of the gallery directly into the page’s content. The use of term “site:” in the search criteria, when the Google API is enabled, indicates to Google that you want search in a determined website, however, if you have included the website when the search context was defined in Google, you simply should enter the terms for searching without the “site:” part.
Best regards.