Kathryn, you can use Google Analytics to have the know how of all the traffic you are getting on your website. Basically, in Google Analytics, traffic is divided into three types - direct traffic, search engine traffic and referral traffic. Here are the answers to your questions:
-When you look into organic search engine traffic there it is divided into total traffic, non-paid traffic and paid traffic and you can easily figure out the exact traffic through various sources. -Organic traffic comes under the search engine traffic where as the traffic through gmail comes under referral traffic and it is shown like “mail.google.com/referral” -Under the organic traffic you can check out the paid traffic by clicking on paid underneath the number of total visits -From the content network, I guess you are talking about the website where we submit content and if it is so, then answer would be that this traffic comes under referral traffic and not organic traffic as it refers to the website.
I hope you got the answers to your problem. If you have any further query, please do post that.