1. It would be nice if the calculated fields would treat an empty supportive field that builds the total calculated field as a "0". I have a calculated field that merely sums up 4 other fields. If any one of them is empty there is no value in the calculated sum field.
2. You should be able to calculate off a calculated field. Scenario is if you are measuring multiple values that build to a total opportunity in each account you may then want to apply a percent of business to that total based on multiple variables so you have a field that is used to input that percentage. I understand you could write the calculated field to have a static percentage applied to that sum but each account opportunity is different and modeling according to those variable is crucial to more accurate forecasting.
3. You should be able to edit certain elements of the supportive fields without needing to delete the calculated field. You also should be able to link supportive fields (maybe you can but it is not working on my v16 Premium).