On asset import, check the option for Generate Lightmaps. This dialog on appears once and you only get one chance
This is meant to be fun right? :-( Well at least it looks KINDA AWESOME!
Use prefabs properly. Prefabs allow you to change every instance of an object in the scene in a single location. However the UI is different to most other packages I've used. In MOST packages when you make a change to an instanced object you are asked if you making a change to only that instance or all of them. In Unity it works the other way around, the changes are always local unless you apply them using the prefab dialog: