Dunning letters - AR

Hi -

We are in the process of setting up Dunning letter and everything seems to be straight forward except a few minor items listed below and any help is appreciated.

1. Peoplebooks refer to a pre-requisite "·        Specify whether to use item-based addressing or customer-based addressing." in setting up dunning letters. What is the navigation to set this up?
2. Remit to address - For some reason only the country is populated in the dunning letter and not the full address of the Remittance. Where can this be changed?
3. How can dunning letter be triggered from Workbench?

Thanks,