1. You can get the game here on itchio if you like, of course! It's the same as the Steam version, and all future updates will be free and come at the same time. The main difference is that Itch doesn't support regional pricing, so if you're using a currency other than USD then Steam may have a better price for you. You can also buy games on Steam and mark them as "private", which does prevent others from seeing it's in your library or that you're playing them, if that's your concern. There's a dropdown menu in the shopping cart page to choose that option.
2. Each route is going to have three chapters, so the story will be done after that! We can't promise we won't add to the game after that, but that should just be fun bonus material, if we're feeling like it. That said, all the routes currently have very intense cliffhangers in Chapter Two, so if you want to avoid that then I'd suggest wishlisting the game or following us here on Itch and waiting for it to be finished.