Hello,
1. About opening the form on new tab, you can have popup https://wpquark.com/kb/fsqm/fsqm-shortcode/add-popup-form-shortcode/
2. In the frontend, it still breaks because the theme or some other plugin is aggressively overriding some CSS rules in a way they shouldn’t. You can show me the form and I will take a look and point you to the conflicting system.
3. About double submission, I haven’t faced anything like it before. So kindly share the URL where the issue is present with instructions on how to reproduce them. I will take a look.
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