Hints for importing buildings

• What will happen if building present in you dataset is already mapped?
• What will happen if building present in you dataset is already mapped as man_made=storage_tank without building tag?
• What about demolished:building=yes marking recently removed building? Or some other use of lifecycle prefix?
• Is your dataset including demolished buildings (must not be imported into OSM)?
• Is your dataset including fully undeground buildings (location=underground)?