ADO and PostgreSQL functions

Hello.

While I was working with Access Projects (Access front-end with MSDE) I was
able to call stored procedures by using ADO command and parameters object.
Now I am trying to migrate my database from MSDE to Postgre and I'm
wondering about stored procedures on Postgre...I couldn't find such
expression in Pg documentation, so I suppose that there are no such thing on
Postgre. On the other hand, I could see that functions could play such role.
Am I right?
If that is so, how can I call such functions from the client (MS Access, for
example) ? I couldn't call MSDE functions from MS Access using ADO, because
ADO recognize only stored procedures (adCmdStoredProc), so I suppose that
the same problem could be with Postgre functions...
How can I use Postgre functions as recordset for my forms and reports in MS
Access? How can I call and execute parameterized functions?

Thanks.