1. Does your billing manager module renew roles based on paid invoices paid online by users of the module?
2. Can users renew before their role expires( i.e. when they receive the invoice) , thus resetting a new renewal date?
1. Yes it will. For example if you configure the module to add a user to a role with expiration days set to 365. When the user make payment and they are not a member of the role it will add them to the role for 365 days. If the user makes payment and they are already member of the role then the module will add 365 days to the expiration date of their role.
2. Yes, users can renew before their role expires and the module will reset their renewal date.