Could a man who didn't fit the established standards of beauty or who didn't identify himself as handsome become handsome as a crossdresser?

Somewhat but not dramatically. An average cross dressing not handsome man can become an okay looking woman but will not usually morph into a knockout.

Do you think crossdressing can bring any benefit to your intimate, personal, social and/or professional life?

If you have truly accepted yourself as being a CD, it can definitely bring benefits to your personal life. If you really haven't fully accepted it, CD'ing can negatively impact your personal life. As for bringing benefits to your intimate, social & professional life that is the exception rather than the rule.