My second question is, when the Nexus comes by after Soran destroys the sun, it clearly goes over the remains of the Enterprise-D. Does this mean that each and every person on the ship had their own illusion like Kirk, Picard and Soran?
I think the planet and Enterprise D were just destroyed by the shockwave of the destroyed star and not the Nexus itself. It crashed in a valley and Soran had set up his operations on higher ground where the ribbon was going to pass. As I understood it they were all just killed and not inside the Nexus.