Lantai means floor, but not floor level, right? I would use tingkat tujuh to specify my office location in this sentence!
unfortunately yes, it can be used that way. usually for building level we use "lantai", "lantai" is more common to address a specific floor level, i have never heard people say "saya tinggal di tingkat ...". "tingkat" is more common to mention how many levels a building has. i dont know if using "tingkat" is correct or wrong though. hope this helps!