Service qualified leads are contacts or customers who've indicated to your service team that they're interested in becoming a paying customer. An example of an service qualified lead is a customer who tells their customer service representative that they'd like to upgrade their product subscription; at this time, the customer service representative would up-level this customer to the appropriate sales team or representative.
Just think about any relationship for a moment. How long you've known a person is incredibly important. It's not the be-all-end-all, but it is fundamental to trust. If you've known someone for years and years and other people that you know who you already trust can vouch for that person, then you're far more likely to trust them, right? But if you've just met someone, and haven't really vetted them so to speak, how can you possibly trust them?
Affiliate marketing is the art of marketing products, services or information for others. It doesn't require that you ever house or warehouse a single thing. But it does require that you have an audience to market those things to online. Without that audience, whether it's through search engines like Google or social media channels like Facebook, you'll find a difficult time with affiliate marketing.