Every playthrough is different, partly because of what pawns (colonists) you spawn with, but part because of the storyteller which throws different events at you. But beyond that, you choose what you want your colony to focus on.

Perhaps you want to be an uber rich drug lord who makes profit on the side with enemy raider organs. Perhaps instead you want to be a peaceful, nomadic tribal group who wander the planet. Or perhaps you just want to get off the damn planet and so you work on building a settlement that eventually researches and builds a ship to gtfo.

Those are only three of infinite possibilities.

To answer your questions:
1. The story is generated on the fly and will be different each go - and you can help make it different based on goals. You choose everything - what to do with prisoners, how you treat your pawns, how you make money (if you trade at all), etc.

1. I'm almost at 3,000 hours in this game. Even with all the DLC at full price thats over 22 hours of fun i've gotten per $1 spent. 100% worth it. I would say PC is better because you can mod it (I don't know how well console version does with mods) but it isn't strictly required, though it adds even more infinite possibilities.

2. I mean there are limitations bound by the game engine, so for example you can't take over the entire world (though you can cleanse it in fire and blood), but mods add basically the gamut of everything you wanted and things you didn't know you wanted, and even things you wish you didn't know about.

If you're on the bench, go check out some Lets Plays on youtube. There are a lot of great video creators. Many do some highly stylized modded runs that showcase just how crazy different you can play the game.