I've found, some, of the answers - but thanks for the page reference for 99-100 results.
Collisions only use km/h - I believe - in the text. I guess you could use km/s too and just divide to get km/h and then divide by 5... it's still be quite a high OB... which makes all kinds of sense, I know.
It came up in our last session due to them navigating on the shadow side of Saturn, well within the orbits of the inner moons (Tethys, etc), which I would think is within the gravity well of Saturn. In the darkness they failed on their scanning and sensor checks, so they didn't see the black/grey massive starship looming ahead of them ... I let the Pilot make an evasive check... and they collided. I decided it was a tiny critical, even if the ship is a lot more massive, due to the fact they just clipped a "corner" on one of its sides.
By the end of the session I let them level up, they'd managed not to die, locate a way on to the mysterious ship, they explored it, fought some space ghouls, managed to hack into the network to shut down two security robots just as they were getting ready to let loose some machine gun madness. They discovered the name of the ship and, at last, a working terminal to access the ship's systems.
I felt rusty going in, and the players were all new to this system, but not to the hobby. All in all I think they liked it. But yeah, I need to get them to level 3-4 before I let loose the full plans...