Setting up/configuring eNewsletter plugin

Have 13 separate wp blogs managed by ManageWP. ISP is Westnet and hosting by D9 mostly plus HostGator. Have installed eNewsletter and trying to configure but some queries. Have printed eNewsletter guide. Have approx 17,000 users total above blogs. 1. Which provider actually processes the emails 2. My users use gmail, hotmail etc so how do I know which port to allocate. 3. I am setting up first on bloggingwithkevin.com. Do I use smtp.gmail.com as per guide or mail.bloggingwithkevin.com 4. Do I repeat this setup process for each blog separately 5. How is cPanel involved in the whole process if I'm not using special themes etc. Does this mean I need to create new webmail addesses in cPanel for each blog eg mail@bloggingwithkevin.com 6. Do I need to set up unsubscribe or similar or do the users simply do this by deleting their account.
Many thanks Kevin Johnston
user=imwinner