As for formatting, you will want to put your duties in paragraphs and your accomplishments in bullets. That way your prospective employer can easily see your job descriptions and find those accomplishments quickly.
Don’t forget that in most cases, less is more when it comes to a resume. When an employer has 30+ resumes to read, huge blocks of print and long lists of bullets can get to be too much. A high impact job description will be clear and to the point.