You can access Zoho Invoice from your Google Apps domain. To do so, please refer the steps that follows;

1. Log in to Google Apps with your domain.
2. Select and choose Zoho Invoice from "Your Services" list and login to Zoho Invoice.
3. Now you will be able to access Zoho Invoice.
   • For more information on this, refer this link.

To import google contacts,

1. Click "Customers" tab.
2. Click "Import Contacts from Google Apps" link.
3. You will get the list of contacts from Google Apps.
4. Select the customers you need to import and Click "OK".
5. You can see the success message, "Your Contacts have been imported from Google Apps" if the contacts were imported.​