Hi Harry,
That code was pulled directly from MailChimp. They have a feature to build a pop-up in their editor, then it generates the code to put it on your site. Based on what you said, it sounds like it might be an issue they need to address?
With regard to #2 above, are you saying that other plugins may be causing those strange products to be added? Just wanted to make sure I was understanding.
Thanks,
Trask