The limitations of changing public IP addresses of CVM instances are:
A CVM instance can host up to 5 websites, and each website can bind to multiple domain names.
Yes, as long as your CVM instance can connect to the public network properly.
You can access an overseas website from your instance only when the website satisfies the regulatory requirements of the country or region your instance is located in. Ensure that your CVM instance can connect to the public network properly and that the website complies with regulatory requirements.
If you have reached the maximum number of pay-as-you-go instances that you can purchase, you cannot purchase more pay-as-you-go instances. For more information, see Purchase Limits.
To query the use limits and quotas of CVM resources, see CVM instance use limits in Use Limits Overview.