1. I need to have more than 1 rule active at the same time. Is it possible?
Yes, you can have more than 1 rule active at the same time. In fact, you can have as many rules active as you desire.
2. How do I add a rule?
Select from any of the categories available. For more information, see this article.
3. Is there a way to prevent certain customers from being auto-tagged?
No, there is no way to prevent certain customers from being auto-tagged. Instead, you will have to manually delete tags.
4. Will previous customers be automatically tagged after setting the rule?
Previous customers will not be automatically tagged unless new orders come in afterwards.