These settings are pretty self explanatory.
Force user registration
- Users can checkout without a user account - no need to register as a user in order to purchase.
- Users must registers before checking out - Has to enable the wordpress settings - Anyone can registers under WP Settings -> General
Shipping same as billing
- Enable shipping as billing checkbox with address fields
- Users must re-enter shipping address
Security and encryption
- Force user to use SSL - This option is usually required for payment gateways with SSL requirements
- Allow site to be used insecurely and encrypted - Should your payment gateways does not require SSL, this option should be used.
List all the fields during checkout. The default checkout form should not be deleted as our shipping and billing often look at the default fields variables.