Rodo only spawns after the quest is accepted, thus it should be impossible to kill him before accepting the quest. Are you mistaken Rodo for another NPC that robs you? Rodo appears at night by the isolate docks in the Northern Inoria (outside of the city). See
here.
Can you add more details to what you mean when a Companion disappearing from where they should be?
If you dismiss a Companion and they don't appear at the spot they appear to re-join you, the most common problem is the map needs to be re-set to reload with them on it. Staying at the inn for 12 hours does the trick, so does just playing the game long enough for the map to reset on it's own.
If you tell a Companion to wait at a spot (but don't dismiss them), they can still catch up to you if you get too far away or leave maps. It's part of they teleportation thing they do to stay somewhat near you.
If they're not spawning at all their original meet points, where you meet them for the very first time, that is odd.