The game is about blowing stuff up, but you need to build something up before you can do that... -so, if you cluster asteroids, can you create a planet? -if you cluster moons, can you get planets in their orbit? -if you cluster planets, can you make suns orbit you, or if you don't do your math right, crash into your "carefully harvested" planets? don't know if there are any posts about this, nor were the private discussion page is.
I think the stream answered most of this, but basically you can technically try to move planets, but due to the area/volume ratio really hurting for planets, you're not gonna be able to do much. Also, take a look at jupiter, all of it's moons are a fraction of its size, it would never orbit them if they were put together. Same thing for star and planets usually.
Originally I would have debunked all of these but based on live stream q&a I definately have widened my ideas in the scope of the game. saying that though. 1-I don't think you can "mash" asteroids together to form a new body of mass, but most likely crash them together. 2-possibly, orbits and functions in game are heavily debated in terms of depth, because of course you couold otherwise end up wizzing planets out of orbit and effectively ruining a game accidently. 3-pretty sure suns have been described as aesthetic centre points of solar systems but not actually functional in game terms at least in the way you think. But really, in the next 9 months anything could happen, considering this is literally the "draw awesome stuff and have pizza idea parties" stage you will find out a lot more by being patient and keeping an eye on updates. Sorry I can't help more.
40 man game, with 4 friends, and maybe some randoms, please cluster the complete galaxy together. If they make it anything realistic, at some point gravity will be high enough to liquify oxygen at 500 kelvin. secondary, high gravity is great. If something is crashed into your cluster, it will completely break and split in pieces, but it will not fly away. Hell, at some point you can just scoop up planets on the passing by. I write this, not only because i think it would be awesome, but also for how good the physics engine is/would be/could be. (and some people want deatstars, this is my version.)