Changing the default "USD" Currency symbol in Appointments Plugin


I got couple of question,

1. Is it possible to change the default "USD" currency to something else that's not listed on the Appointments + currency selection drop down menu?
My client is not gonna sell appointments, so the Paypal payment is not needed. The price of the appointment should be in the native currency (LKR) not in "USD".

I found this thread about this but the support person hasn't mentioned how to perform this step by step:

2. Is there an Appointments + integration with Woocommerce?