1) Yes, the allow blank option must be applied after running the wizard by editing the Server Validation server behavior.
2) You will need to edit the Server Validation for the URL Validation type to apply the Allow Blank option.
3) I have logged a bug that changes to the initial state of list and menu form elements are not sticking to be corrected in future update.
4) the font properties of a file field are not treated the same across different browsers. the reason for this is that the browse button of the file field is an image that is generated by the browser. this is why the browse button looks different from one browser to the other. it is not possible to control the look of the browse button through CSS, this why there are no options to set properties for the file field.
5) yes, there will be an update released to cover the issues you have reported.
