Corrections needed for our custom website. SEO and coding experience needed.

My businesses custom website is struggling due to some basic coding errors that have created: Dupe content Dupe url structures Poor utilization of canonical 302 redirects information that should or shouldn't be indexed There may be database issues. At this point I cannot make heads or tails of it and need it corrected, or a breakdown of what it needs to be corrected immediately. I am basing my observations off of a report I ran, and compared it to our competition. You need to have a strong understanding of SEO and Webdev as I do not want to have to explain what is wrong. Much appreciated