Qustions About Updation of my template

I have some Questions about Update of my template.
I want to update some files in my template, Is that I have to provide the new theme demo URL or should I have to update new files to existing URL? will it cast any impact on my existing template?
(as I have One page template approved and I want to update Multi page)

Is that any way to link WP theme to HTML template For submission? or I have to submit WP theme separately?
Can I update Theme preview as well ?
Thanks for your answers.