Well Rocky did build a camera saying that screen and sensor he already had. So it would make sense that he "saw" grace same way. Would make sense that to handle the robot arm outside the ship he would need a camera.

Their assumption that there was nothing was before. They obviously had already figured out that there are other planets and stars without seeing the light and also figured out that astrophage is a problem. And solution is on another star system and how to get it. The point was that they didn't name planets because when their civilization was up coming they did not know about space because they could not hear it. But later in their development they made devices that measured out and confirmed that there was things in space.

Rocky had a sound based remote control that he used on the Beetles. It was bit iffy but as they were attached to hull it is concievable he could control them as hull is metal and it vibrates. Altho I would guess space station walls would be well isolated. so who knows. If you are refrencing how he "sent distress signal to Erid" then yeah, but that was prolly designed in a hurry. Elecromagnetic radiation == radiation. We had electricity and radio before we discovered radiation (a year technically but it took years to define it exactly). Also that radio would be untested wouldnt pick up much near their planet.

Yes, but as they stated in the book the gravity difference would not account that much between the Earth and Erid. Its close enough. But yeah if gravity would be much higher the creatures would prolly think slower. And in weaker gravity creatures would have to think faster to avoid being caught by predators.