The house that they sold seems nicer than the one they apparently are currently living in - but maybe it was too big for them with their children starting to leave the house? I assume only Benjamin (16) still lives with them; Isabella (22) and Samuel (20) will no doubt be home once in awhile but I assume they don't permanently live with their parents anymore.
Yes, he does. In 2017 it was reported that he owned property at 590 different addresses, including 349 in Amsterdam. Not all of them are houses or apartments, offices and retail are also included. Most of them are part of a holding (BV); 102 are private property. Of course, apart from a few houses for personal use, the large majority is rented out.