Well you have the ships graphics and I will add more objects in the space. Problem with zooming in the planet that than I would need to take down the map size to have place for the planets (even If I make only 14 for each player.) But if the maps will ever get higher space than 256x256 than I will do it. Yeah I could further decrease the model sizes but its already really decreased... I will also add lots of images to the dialogs, I might add that they will change as you progress or the planet models might change to as you progress.
You're just need to make units small enough to have an effective control over the map. You're just triggering it to have 3 zoom in/out variants for Galaxy Sector, Star System and Tactical camera variants. As a judgement over your Vid's, it seems your ships are not quite tough enough to have a tactical feel over starship battles. There could be longer acceleration rates and slowing weeapon types, but combat in space should take some time to make tactical decisions.
As about planets, they just need some different textures depending on their abundancy type. Adding some local features like nebulae/asteroid belts (using fog/wind doodads with tweaked parameters) will help to navigate map easier.
For a couple of other major ideas, I'll leave them for myself as I've wished to implement them in my SC2 version of Space Empires project later, although I could cooperate with this one somehow, to not make endless copies of the same map concept.