1. Give free shipping to some customers?
2. Give different sales tax to customers in the same county?
3. When adding a new customers, can you copy over the details from an existing customer, so you dont have to enter everything in from scratch?
4. Can each customer have different pricing, adjusted at an individual product level, but not adjusted by percentage?

Thank you for any suggestions! I've looked into zencart and magento so far, but I dont think either one can do all of the above. A paid solution will be ok if none of the free ones can do all of these things.