1) we did consider this, but DW doesn't support nested loops and we wanted to stick to using the DW recordset and repeat region when creating the pages, so we would have to travel outside of the available DW capabilities to accomodate this. This was left on the chopping block when implementing the last version, but could be added in the next if it is a common request.
2) The page created is based on a recordset. This is the benefit of the above decision. So although you can't use the wizard, you can easily edit the recordset on the include page after application to fully customize your query. We didn't want to "reinvent the recordset" in our interface, so we made sure to use one on the page that you can fully edit after the fact.
3) Again that is to integrate with the standard DW recordset... notice how similar it is to the "Simple Recordset" server behavior in dw. Open up the created include file and feel free to add as many parameters and complex query additions to the recordset used. You can add your nested loops as well (by hand since DW won't let you nest repeat regions) as long as you are careful to make the necessary css accomodations for those levels.