1. Several ways of doing it
If both of your tables in the same database you can just use sql as data source and do it this way
Select from customers where address_id not in (select address_id from adresses)
or
Select from customers where address_id in (select address_id from adresses)
Or
you can use in InList function within Data validator to validate the data
by default you have something like this
Data Reader=>Data Validator => Data Transformer => Data writer
Double click on Data validator and add InList function
Double click on InList function and use something like this sql as a source
select distinct address_id from adresses
Please watch our OnLine tutorials they will give you a good start
2. Double lick on data reader object, click on Data restriction tab and check you settings