For some fields (ie. strings, booleans, numbers, etc.) having an option to setup a default value on creation would be awesome
Yes, much needed!
Will it also be possible to set the field so that it can't be empty? i.e. it's either the Default or one of the other options, but not nothing.
Yes, as long as you add a "required" validation on the field!
How will default values behave if fields which previously did not have a default value are now given a default value?