Search engines work hard to decipher the content of a page. By using structured data, you will provide search engine explicit clues about the meaning of the content.
Redirects are used to send search engines and users to different URLs from the ones they requested. When you are redirecting one URL to another, you should follow the best redirect Practices to retain SEO value.
If used properly, canonical links can solve the duplicate content issue. Yoast has published a long guide on the topic.
