Hi there
I recommend learning the best practices for redirects, as well as hreflang attributes and language tags - you should also read into country targeting your sites in Google and Bing - this is a big deal for international SEO and targeting.
I would also look into your dynamic URLs by reading through this resource from Google on potential duplicate content - this will help you categorize and manage your URLs, helping Google understand their purpose. You should also check your internal links and sitemap to make sure that there are not dynamic URLs listed there.
This will require your web development team as well, so make sure they read and understand these resources, both for current and future situations. Some of this has the tendency to get pretty technical and indepth so if you need help, know that Moz has a fantastic Recommended Companies page to help.
That being said, 301 redirects are preferred by search engines, 302s passes 0% link juice and most cases should not be used, and all URLs (and their dynamic variations) should have a canonical tag to the preferred URL.
Hope this helps! Good luck!