Thanks for the detailed feedback! Really appreciate it! Next time I come out with something, remind me of your comment and I'll send it to you for free :)
2. I skipped this step because chatroom apps are fairly common, and I didn't want to reinvent the wheel. But you're right, for most apps you'd start out with pen and paper to figure out which elements to include and the general layout of the thing.
3. Bad decision on my part, sorry. I thought it would be too boring to have the exact same layout on every page, but when you put it like this it does make more sense.
4. Good point as well, for some reason once I decided to write an eBook my mind went straight to a book-like portrait format.
Changing the format now would take a lot of time so I don't think I'll do it, but I'll definitely consider it from now on. Thanks!