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Yes, You should exclude coupons. I do, personally, at least.

You are wondering why a 301 creates an entirely new URL is because it redirects to another outside link it can be outside of your domain or inside. Your domain the content of your site obviously was from the links units on Google does not look too kindly on sites that we could possibly not being wanted by some households as it is not for children. I only use screaming frog  to do it quick audit of you links your site free up to 500 pages http://www.screamingfrog.co.uk/seo-spider/ Here is best manual for screaming frog http://www.seerinteractive.com/blog/screaming-frog-guide Honestly you may have some trouble because the content of your site this however if this is illegitimate business Please do not take offense at all as some of the keywords you were drinking for our big negatives in this business For us that are not making those sites. I hope this is going to help, Thomas