Can I add charts as 'result' of the calculator?

Yes, (only Pro plan). At your spreadsheet you need to set one different 'name' to each chart. Once uploaded the spreadsheet, go to the layout editor and drag&drop the 'chart' widget from the editor left panel to the position where you want to place the chart. Then select at the right panel the name of the chart to be shown. You can place any number of charts in a form, and also include them at the email and or pdf export.