Structuring my DB class objects.

I am trying to get to a point where we don’t have to do any SQL/Database coding. So far I have four classes, Connection, Lookup, Customers and Customer.

The Connection handles the connection and holds the Username, Password and Server properties.
The Lookup handles the SQL for returning Customers from the Oracle Database and passes the data to the Collection.
The Customers class does the adding to the collection, the Count, Remove etc.
The Customer class holds the defined variables and the ID for the collection.

Now, my intention is to add more SQL functions to the Lookup class, but I will need to add classes to handle the collection population and collection properties.

How many classes can I add to my Project/ActiveX dll before it goes belly up or I lose control of what’s going on?
How do I get the data into a Data Grid? Do I add yet more classes for Customer_Fetch?
Has anyone got a design/model/document on how they have done this?