Re: farm out
"eyeballs" means, in this context, the number of people who visit the page. It's a synecdoche.
The point of the piece is that some of these sites get many, many visits. They do this, even though the content is bad, because they have figured out how to show up high on hits created by Google searches. Because they have so many visits, they can charge high rates for their ads. (The logic is, "A lot of people come here, so you should pay well to be seen by that many people.") However, it's a poor use of advertisers' money to advertise there, because the poor quality of the content won't keep the visitors on the site for long or engage their interest.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.