Can you edit a planet any more extensively than the options in the system editor? I'd like to create a planet which is nice and smooth (no mountains or rock outcrops etc) but with several long fractures on the terrain to divide the planet into regions. Is this possible or is it luck of the draw with seeds?
It's 'luck of the draw' through procedurally generated planets dependent on the seed. It is likely that people will make mods to have a fully featured planet editor, but this will not be a vanilla launch feature.
because the seed number goes into the thousands, does anyone actually know what the seeds affect? like higher the seed number, the more moutains you get, or the more factures you get ect... just seems a bunch of random numbers to me that don't really affect the terrain directly, its just purely random. Is that right?
Seed is a set number for the generation, if you use the same seed twice it'll look the same (with the same biome and other settings set.) Haven't you played Minecraft before?