Is there a way to store multiple destinations as favorites? if so how many does the unit store?

The address book will store 100 or 200

If you mean sequentially, I don't think so. You can select waypoints each time you punch in a new destination, and as mentioned before, you can store destinations in the address book, & you can use it even if you don't know the address of where you are: you can choose "from map location" and then it marks the spot where you're currently parked.