I'll address the hollow thing first. Unless you're working with voxels, but rather with polygons, like 99.99% of today's games, everything is hollow. This is because each surface is comprised of polygons; these are one sided surfaces defined by 3 vertexes each (possible to work with more but engines just subdivide them into 3 vertex polys). One sided surfaces means that they are only visible from one side; if you found yourself inside an ED planet, you'd see stars right through it. In short, every 3d model in every game is hollow. It's how our current 3d technology works. It doesn't really matter as an average player will never notice, for as long as collisions are on and you don't clip through anything.
I can't really answer your second question without having been on a surface of an ED planet yet. What I will say is that from space, they do indeed look correctly sized to me.
I appreciate what you said about 3d, yes I'm working voxel so different. But hollow isn't an issue and shouldn't be an issue. But its scale I'm looking at, to me they don't look anywhere near the correct scale. But until we get to the surface, we don't know. There again, in the video I am referring to, he got to the surface of the planet and collided with, yes granted didn't clip through
.
But at the surface the size/scale was not as I would expect it to be. That's if FD are correct in what they're saying, i.e. full size that planet would be over 4000km diameter, the curvature would be miniscule or indeed not noticeable, whereas its quite noticeable in the video.