1. The door is too small, the player gets stuck
2. The model seems to be floating; it moves when you shoot it! I feel this may be a property inherited from the "vehicle" class. Any ideas how to fix it (it currently weighs 800 KG but still moves... can you show me how to make it a static prop? Currently when you 'mouse over' the shack it displays its name, something that doesn't happen with the standard buildings)
A couple quick hints that should help your structure.
This should solve any issues with floating:
-Window ---> Named Properties
-Right click in Named Properties window---> New
- autocenter 0
(Do this in all lods for safety and consistency)
-Make sure it's placed appropriately in all lods, it should now be reflected in game as it's oriented in o2.
As far as the rooftop being transparent from within, I imagine you've already solved this problem; but there are a couple of solutions. Copying and pasting in the same area and reversing the faces is one option if you don't mind it appearing paper thin at some angles. A trick that works well with this method, particularly for windows is selecting each face or group of faces (facing the same general direction) and 'Faces' ---> 'Move Top'.
This prevents glass and other transparent materials from hiding objects behind them.
All geometry LODs(Geo/View/Fire):
Simple boxes reflecting the model's relative shape, often times you can use the same modeled geometry for each of these lods without error. Make sure to add mass to the 'Geometry" lod's vertice, make sure you add corresponding rvmats to the 'Fire Geometry' lod (ex: CA\data\penetration\metalplate.rvmat). You MUST 'Structure ---> Topology ---> find Components' for each of these Geo lods.
As far as your building moving and turning black, there's certainly something silly in your config inheriting awkward attributes. I hope some of this information helped.