Desperation causes me to try yet again to build a form

1 & 2) The border is automatic... you need to add border:0; to get rid of it in the css.
3) The easiest way to add another field would be to cut and paste one of the ones on the page. The form builder already defined the structure and CSS, so adding a field is just a matter of copying an existing one.
4) Yes, that is exactly why I wouldn't go back into the wizard and use the builder as an editor. Use it to build the initial structure but then copy the code to add a field.

Definitely a bad decision to start from scratch. You would lose all of your edits and be starting over. Copying and pasting a field and renaming it would take much less time.