Thanks for your opinion!
First, the easier question - yes, it's a harem game. You can be with all girls or just with one or remain completely alone. That's your choice.
Second, decisions - 0.3 will introduce the first world where your decision have an impact on its future. In my ideal scenario, what you do across all the worlds will be important by the end. I'm still not sure if I'll be able to achieve that, as the end is quite far off, but that's what I aim for.