Hi @Arun-AK We are happy to have you back! A course can only be switched from Free to Paid once. If the course is switched from free to paid and back the promotional emails will be disabled permanently so, even if you update your course content, the promotional emails won't be enabled again.
Regarding your question on creating a new course or updating it, many instructors have found themselves uncertain about this, and I have found a couple of threads that may be relevant.
Do I Update My Bad-Old Course or Do I Make A Brand New One?
Creating a new course or updating the whole course with new videos?
Updating courses: when it's worth it, when it isn't.
You can also do a quick scan in the community using the search tool. I think you can find even more information about it by using keywords.
For your second question, I'll recommend you to reach out to our policy team at policy@udemy.com they will be able to provide you with more details on what is allowed and waht is not.
Eliana Cerna
Udemy Community
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