Presentation of amounts and dates in Rollbase and Portals

I need to present all amounts in my application with a decimal comma in stead of a period. And a period on the thousands. And if I export to my (Dutch) Excel, those amounts should be interpreted correctly. (How) can this be done ? And... I found the way to present dates as dd/mm/yyyy. But actually we use dd-mm-yyyy. Is there a way to implement that format? It would be real nice if Rollbase would recognize it as a datefield while importing from Excel....