I stayed at Yankel's place for a week - and it is the perfect location. It's near several metro lines and is a quick ride away from the airport via the RER with a change to a metro line (the change is easy and doesn't require you to leave the station). I think most of the major tourist attractions are less than a 30-minute metro trip away.
Getting into the apartment was easy - I was provided the door code to enter the building and then a code for the lockbox that contained the apartment key. The place itself is kind of no frills - but that doesn't matter if you aren't planning on hanging out there a lot. As a note - it is a fourth floor walk-up. It's not a tough climb, but just giving those a heads up who might not be as mobile!
The neighborhood was quiet, has lots of dining options. There is a convenience store below the apartment and a laundromat a few doors away.
Yankel was really responsive to any questions I had, so I appreciated that.