I assume each planet follows its own distinctive rules, how does that work if someone travels from one planet to the other. Is he then subject to the rules of the planet? And is that a system similiar to "low security/high security" which punishes acts of crime differently, like a rogue planet with high risk and reward?
Yes, you're subject to the rules of that planet, which don't include only PvP rules and the "criminal system", but also racial buffs / debuffs, and more. Tartaros is probably even more than the "rogue planet" you're suggesting - it has open PvP and zero consequences for criminal actions.