Yeah, agree that 45-day refund policy is a great option for readers and thus increases the likelyhood of a purchase.
Regarding the questions:
1. I thought courses were video, similar to Udemy. I just went through FAQ and found that video is optional. Courses has quiz, certificates, etc. Personally, I'm more interested in an interactive programming environment where users can execute code snippets and exercises can be solved from the website itself. I've also thought about creating a desktop application as an alternative.
2. Thanks a lot for the offer, I would like to think about it. I'll let you know if I'm interested.