The only real plot is that we need to get the world setup for colonists. We won't get any until we are ready, though, as we will have to tell them to come (though there may be some refugees at some point.) I designed my ship as a kind of cargo-hauling space-plane, but you can design your own if you want. Just remember that it can't take off/land from a planet unless it generates more than that planet's gravity worth of thrust. My ship takes all the reactor can put out to launch from Earth with a full load.
Antagonists will really depend on if you need them. In the interest check there is a guy that wants to be a military team, so he's going to have to have pirates follow if he wants to have someone to fight. There aren't any higher-order animals small proto-fish and mollusks at most, or worms.