I have an issue where if the text/content is larger in height than the page size of my document, it does not flow to the next page. I have spplied these settings on my master page 1
The result of a text search gets wrapped in a span if it is not a discrete element. In your case the @My Content Here@ text is probably followed by other content.
I think things will work better if you use replaceWith() instead of html(). That way the span gets replaced with the Hello World paragraph.
Yes, in some scenarios the current version of Connect adds the “dynamic” class to scripted content. This is meant to trigger an internal style rule with user-modify:read-only, ensuring that scripted content is read-only in preview mode. This is just cosmetic, it should not affect output.
Adding that class is actually legacy behavior. We are no longer adding it in the upcoming CEF-based version of Connect.