Once installed is there the option to include or import existing customers

Yes, if you would like to give your existing customers points to introduce them to your loyalty program please provide us (support@loyaltylion.com) with a CSV file with the following:

Column A: Shopify ID
Column B: email addresses
Column C: points - list the total points each customer should be imported with

If you do not want to give them any points to start with you do not need to import them, once they log in they will be pulled into the loyalty program.