Hi Jefferz, these are very reasonable questions, sorry for the issues.
1 - Galaxies are currently works-in-progress. What's in there now are essentially exactly as you said -- placeholders. We want to make improvements to these, we just haven't gotten around to them yet. They shouldn't disappear when you place them, though. I don't see that here. Does it happen every time?
2 - Check to see if you have Displacement Mapping disabled. It needs to be enabled in order to produce non-spherical shapes: Home > Settings > Graphics > Impact Marks then turn on Displacement Mapping.
3 - We have improvements to fragmentation and collisions in progress as well. I'm wondering if you have low settings enabled, though, which may have been set by default if you are running it on lower-end hardware. It sounds like this may be the case given your other questions. Check Home > Settings > General > Simulation Performance. Try changing it from Auto and see if you notice any difference.
Hope this helps!