Needing Volusion Familiar worker to add custom features to Volusion Site

We currently have a Volusion website that does most of what we need it to do but needs custom added features.
For example, we need to add net 15/30 terms, create checkout options such as 3rd party Shipping account or shipping via our shipping account and adding shipping costs to each separate item based on a shipping breakdown we provide instead of applying shipping charges based on the shipping cart total.
We need to set it up where our customers do not have to enter their CC every time they want to check out.