How to display currency in calculated field?

5- I'd like to display certain text fields as currency - I found the "Masked Input" widget to display a field as currency.  However, how can I apply that to a calculated field?  If I select that widget, it seems to add a new field rather than having an option to use an existing (calculated) field.

I think that you're referring to the form calculation widget, is that correct?
If so, unfortunately that's not possible within the tool itself. However, if you're embedding the form on a website then you can use JQuery to accomplish this.

Here you can find an example on how to do it.

Let us know if this works for you.
Thanks.