Under #2, be careful with popups or modals that cover other interactions, Google will now penalize this kind of activity on mobile. I suspect we’ll now see persistent banner style replacements on mobile (a strip across the top of the site that doesn’t scroll off the page or disappear until you close it or sufficient time has elapsed without interaction.)
After you have entered your "List Name" you will need to enter a "List Description." Here is where you will describe the kind of information you'll be sending from this list. There is a 400 character limit for the "List Description." Subscribers will see your "List Description" on the unsubscribe page if they ever go to unsubscribe from your list. Once you are done entering your "List Description" click the "Next Step" button.