Yes - it's easy. Just create your query, and then bind the report to that instead (RecordSource property). As long as the fields have the same name - no problem.
Is the form bound? Are you closing it to go back? If so then you could force a save in the form OnClose event - use the button wizard to generate the save code.
If the combo box contains the key field, then it is easy.
In the AfterUpdate event of the combo, build a SQL string e.g.
strSQL = "SELECT * FROM TABLE WHERE KEYFIELD = " & Combo.Column(0)
Then change the recordsource of the form to be the SQL string (Me.Recordsource = strSQL). You can do this...