I loved the show and was furious when it was cancelled.
I saw a few of the TV movies, though I am pretty sure I didn't see the final one. It's been so long, but did they ever mention that baby again in the movies as they progressed? I seem to remember them putting it in some room or cocoon like a house plant because it was that "phase" but I don't remember anything about her after that. The birth of the baby was one of my favorite moments in the series but it seems like they just wrote her off after that as some sort of character mistake.
I always liked how uncle Moodri was able to defy the physics of their biochemistry and step into the ocean with no ill effects. It made me think that maybe the Tenctonese were actually more powerful in terms of their paranormal mind abilities than anyone realized, but that they had simply been reprogrammed to believe
they would die with salt water (possibly as a method of controlling slaves) and actually somehow did it to themselves. I don't think they ever touched on this idea again after the uncle died.
As to why they would all settle there on the coast, that was either a human decision or if they were given a choice after they came out of quarantine, maybe it was just what they knew best. If the salt water thing was
a Kleezong-whatever slave control method, maybe one of the things the slaves did most (mining or some such) involved being close to salt water oceans on many worlds. What better way to keep your minions in line than to have them that close to imminent doom. Thus use their mind abilities against them and make them believe that salt water will eat them alive. It's all speculation on my part, but that was one of the things I loved most about the series to begin with!