To limit the number of records, You have to change the number of rows that will be shown in the query itself and not the report template. Open your query in the Query and Reports designer and check its properties, There is a section where you specify how many records will be shown.
I liked your idea for the surveys by the way, Could you please share your report template here as well?
Sounds weird. Try to create a new query with the same settings and criteria then add it to Workspace and see if it works.
So how i ended up fixing it because recreating the query didn't end up working was to delete the dashboard gadget and rebuild it for each query affected.