To the two questions:
1. No, we load a texture, draw it across some vertices for a bit, and then drop the texture. In terms of the innards of what is really happening, a lot of that is obscured by unity, and then either directx or opengl under that.
2. We could do that for AIW (we do for Tidalis like we do here, except Tidalis has low enough counts of graphics that it never unloads anything), however I feel that AIW's current method is actually better for AIW. It does give you pop-in and a slight bit of stutter there, but we're not talking about something that is frequent and it saves you a lot of loading time overall. In your whole galaxy there are lots of ships that you would not see unless you go to that specific planet; And even then, not unless you zoom in. So why load all that stuff and make you wait a long time (30+ seconds, probably) when you first load each galaxy? Why not just load it as needed, and have a slight stutter when it's doing so? It's loading those on 8 background worker threads, so they aren't blocking to the application itself.