Change field type > impact on calculation

unfortunally its not possible to change the field type of an excisting form field.
Now, what happens if i have a calculation like this:

{field1} * {field2} in lets say field 3
Now I change field 1 to a new field ( i think this wil be field 4? AND I change the id from 4 to 1 (if possible).

Will the calculation {field1} * {field2} in lets say field 3, still work then?

same questions (maybe) is the calculation done on the name or on the ID?

The calculations are based on the field ID and your calculation {field1} * {field2} will no longer work because field 1 no longer exists.