1) That is a css border around the fieldset. It can easily be removed in the CSS
2) Again just adjust this in the css after application
3) The form builder is designed as a builder not an editor. Dreamweaver should be used for editing forms after they are built.
Another user reported crashing in form builder today. I haven't seen it very often, but certainly not unique. I'm testing techniques to prevent crashes in the next release, but I'm afraid I can't do much in the meantime.