Add extra features to your wordpress comments like ajax posting, email notification on reply and field validation.
The clone form option hacks on wordpress default "moveForm" function. If you are using some plugin, theme or custom function that will not use the default's comment_reply_link behaviour then the clone form option will not work. Try disabling any comment related plugins/custom functions.
If you changed the default field names on your comment form, then the validation will not work. Please use this options only if you didn't change any of the default field names.
Yes you can. The notification email will be sent in HTML format.
Use the plugin's forum link on wordpress.org. You can find the link on the plugin's page where you downloaded it.