Questions, answered straight
If something here is unclear, ask — a person reads the contact form.
No. The ladder starts at true zero — Level 1 has no code at all. Each course states its prerequisites at the door, and the free hour tells you exactly where to step on.
One .html file per course, delivered by the checkout as a download. Open it in any browser and it plays: narration, read-along transcript, live demos, exercises and a quiz. It works offline and will still work in ten years.
No, and it never will be. Every price is one-time. the Complete Library includes future updates to the files at no extra cost — a promise attached to the purchase, not a recurring charge.
Not to learn. Every demo runs in a clearly-labelled simulated mode by default. Some builder-level courses offer an optional paste-your-own-key field to go live against a real model — never required, and the key is held in memory only.
Individually, no. A buy button only exists once the file does. The one exception is the Whole Ladder, sold explicitly as "everything current, plus each remaining course delivered the day it lands."
Courses use the natural voices your browser and operating system provide, and automatically pick the best one available. Microsoft Edge ships excellent ones built in. If only robotic voices exist on your device, the player says so and points you at how to add better ones.
Email and you get your money back. No form, no explanation required. A course that did not help you should not cost you anything.