Here's what causes the elevator bug. When the elevator doors close, there is a brief pause before the icon for the elevator call button becomes visible. If you exit the front doors in the fraction of a second between when the doors close and that icon appears, the icon will not appear when you come back inside.
As Malkav said, you can fix this by going down into the basement and using the air vents to go to level 1, and then catch the elevator back down to the lobby. (I'll leave it to you to figure out how to get past the security guard.) When the elevator doors close behind you, the call button will appear again.
Falling through the floor is a pain, but it's never happened to me in the Skyeline Apts. Weird. Usually it only happens in places where the floor isn't level, such as the rocky terrain outside of the Monastery in Malibu.
The reason your computer spells it 'Hengey.kai' is that it can't read the 'ô' that is used in that word; i.e. 'Hengeyôkai'. 'Protege' is the same way, since it's spelled with a tic mark above both e's (which I can't type here). My computer picks up both of these words fine; not sure why yours doesn't.
Venus' dialogue is messed up for me too, though.