Hi Tony,
Welcome to the world of SEO 
I just spoke to someone who had a similar issue (duplicates due to user reviews). There is a relatively clean solution for this and it comes with a fancy name, "Canonicalization". Here is a great step by step for setting a page to rel="canonical".
Basically, you want to tell Google that there is one "source" page for all the duplicates.
Example:
You have a page for blue widgets. Users can review the blue widget, but each new review becomes a new page (problem). If you label the original product page as canonical, your duplicates will be ignored, and the Google bot will be much happier with your site 
It's hard for me to tell how much the duplicate content is impacting your ranking right now, but after you use rel=canonical, you should see some major improvements within a couple weeks.
As for the 302 redirects...you want to fix this immediately! Here is the step by step for 301's.
There are some shortcuts to changing 301 redirects depending on your platform...do you happen to know what your development team is using? Changing 5,000 of these would be a little cumbersome to do by hand 
Keep up the good work!