1. Maybe it's a matter of perspective. I actually find the free plan to be quite restrictive, especially for long term use. The current model is designed to be profitable. The free plan is sustainable.

2. Yes, you can. Just open the web app, click Upload Files, and select what you want. More details here: https://horizon.pics/help/articles/start-uploading-files.

3. Yes, it's lightweight, fast, and user-friendly. It's quite minimal looking, and I've tried my best to make it as easy to understand as possible. Whether that's through clear and concise instructions along the way, tooltips or intuitive action button colour hierarchy. There's no Windows client because I just haven't gotten to it yet. There's ShareX, which is compatible with Horizon.