1.>I got the impression that Nimbus III was a wasteland of planet all but forgotten and ships didn't visit it and there where no ships there, after all surely they had already been used to get off the planet. 2.>Agreed though depending on the plane of the system and the way the reliant approached it they could have thought the other planet was behind the sun as the reliant appraoched and the sun was masking the location of the planet (a stretch I knoother). As for the second part Kahn was so obsessed with beating Kirk he had tunnel vision focusing so much on that one goal that he missed it. How many of us when we focus on one thing miss other things. 3.>If you are talking about the probe in ST IV, remember they where only harmful to humanoids, it almost seemed to be some terraforming on Earth to prepare it for new whale life. as Spock said in the film "Only arrogance would assume the transmission was meant for us" 4.>Agree on the first part, as for the second part passage through the Borg temporal fissure causes the sensors to go down. A line in the film addressed this "They must have beamed over when our sensors where down"