I have two questions about this passage from a book I'm reading:

(This guy in a wheelchair hired a live-in helper ...)

Платил Соловьев более чем щедро ... но, в сущности, тот помощник работал только за жилье. Когда у него появилась возможность приобрести собственную квартиру, он известил Соловьева об уходе.

First what does в сущности mean?

And second, why couldn't the guy get an appartment at first ? Why could he only get one after he moved in with the wheelchair guy? How does that work if you want to get an appartment in Moscow?