2) I enabled the option in the "Image Source URL to Image Conversion" and think the image embed with a url should be converted and displayed but this does not happen.
We've just checked on your website and don't find such an issue, the "Image Source URL to Image Conversion" works fine, see here: https://lingdaoli.com/entrepreneurial-leadership/
You just need to use an image absolute URL like this:
More info here: https://wpdiscuz.com/docs/wpdiscuz-7/plugin-settings/comment-content-and-media/#image-source-url-to-image-conversion
For farther support please register and open a new support topic in the wpDiscuz.com support forum. Here we only support issues related to wpDiscuz paid addons.