Does Scan To Pay and Scan For Loyalty still work if "Order Ahead" is turned off?

Yes. 

Turning off "Order Ahead" for the location in the portal or from the Smooth tablet, will still allow in-store scan for loyalty/payment. This flag just turns off the ability for customers to place mobile orders through the app. However, deactivating the location from the portal using "Active" toggle will shut the location down and not allow it to receive mobile orders and in-store scans.