How do I inform the buyer about a track and trace code?

Just set the proper track and trace code in the order.
Possibly you have a module that already takes care of that for you.

If a track and trace code is present and the order is marked as shipped, the module will take care of informing bol.com about that track and trace code.

How do I handle returns?

The module currently does not support returns.

However, you can simply use the “Partial Refund” or “Cancel Products” function of Prestashop in combination to restock products.
You just need to process the return in bol.com’s back office.

How can I add the bol.com connector configuration screen to the Prestashop Back Office menu?

Go to Administration -> Menus and click the “Add new menu” button. Place these values into the form:
Name: Bol.com connector
Class: AdminBolcom
Module: bolcom
Status: yes