Shipping costs per customer

Hi,

I have a question regarding shipping costs.

For loyal customers I do not want to charge shipping costs.
For other customers the shipping costs must be calculated normally (this is already working).

I can create a customer custom field to indicate if a customer is a loyal customer or not.

As far as I can see it is not possible to steer the shipping costs per customer.

If this is true, how could this functionality be implemented? what code must be added to achieve this?

Another question: I have purchased HikaMarket. Will it be possible in the near future to manage customers in the front-end as well?

Thanks a lot in advance.

Hugo