Reply To: Flat Fee

1. I don’t understand completely what you need there. You can separate them by applying your fee after the taxes get calculated. Or if you use a price field for that to not set a tax for price fields. And the deposite is totally unrelated to this and gets calculated from the full price. So you’ll have to edit that part too.

1a+2. You can select for each tax if it should apply to the price fields or not. Required can be set while adding it. In the current version disabled will result in a hidden checkbox, but that’s fixed for the next beta.
Regards