is anyone aware of a way to make bill to address mandatory on a customer record? It looks like it may require a script.

Did you try customising the customer form?

When you add in an address to a new customer, it already has Default Billing checked to Yes. Someone has to physically un-check this. What is the purpose of making it mandatory when by default it has it checked already.

seems like sometime people are not entering any address, in that case use a workflow to force that