Full disclosure: It's late, and I'm very tired. So it's possible I forget something or talk gibberish xD
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The game is currently under development (beta), with monthly updates.
You may want to wait with your purchase, unless you really like the idea and don't mind bugs, missing features and events/stories.
1. The game isn't the most difficult one, if things go smoothly.. It has his challenges, and mismanagement can easly lead to bankruptcy (which isn't a game over at the moment).
The final game will have a main story with (please correct me if I'm wrong) tasks, but at the moment it's only sandbox.
Despite being "simple", I think you can spend a surprisingly amout of time in to the game.
2.
There isn't a console, but certain keys do activate cheats.
3.
I can't say much to it, but looking at the files you sure can modify certain things.
But when my memory is correct, we will get a tool to make events as well, and they will try to give us mod support.
4.
It's definitely still in development and needs refinement in their different stages. I would say it's rather simple, but in a good way.
5.
We don't really have the stories yet. Only the beginning, but the rest of the main story and the substories are missing for now.
6.
Yes, the idols can befriend each other - or even start to bully somebody they don't like.
There are also events, which shows the envy and problems the idols have with each other.
As player, you can try to get on the good side of the girl and you can romance them. But I haven't done it yet, so I can't tell you what exactly it does (at the moment).
7.
The idols have physical and mental stamina. You will have to manage it, or else they will get overworked. They can tired, injured and depressed.
Every idols also has a trait. Some are positive, some are bads.
They relationship system also added some trivia about the girls (which is great, because it gives them more personality). You are able to discover them by having a casual talk with them.
Oh, and of course there are scandal events.
8.
Personally, I really like the art! The pixel art is well done and has a nice animation.
The idols themself use a paper doll system. So it is possible to get "twins", but that's really just rng. I don't know what's planed, but I think there coming more art (we just got two new with the last update), and maybe we will able to change them?
9.
You have to download the update manually.
10.
The Kickstarter is done, and to my knowledge it isn't possible to give them more sweet money.
11.
Yes, according to the shop page you will get a steam key.
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Personally I think you should wait. Not because it's bad, but from what I understand, it won't have enough content for you (yet).
There are features/event/stories missing, and there are issues like freezing and other bugs. Sometimes really ugly ones, sometimes little problems.
So I feel you should wait for the release, or join the beta later.
Unless you are interesting in testing, providing feedback and suggestion. Just don't expect a full experience yet.
Being said, the devs are doing their best to make a good game.
They always deliever a new update each month, and then one or two fixes for the nasty stuff. So far they didn't give us a reason to doubt, and there is definitly a reason to look forward. I'm having high hopes for it.
FYI, the devs are also active here in the forum. So maybe somebody will come and deliever you a more compelling answer to your questions :)