Re: Working in Ticino but staying in Lugano, Como or Milan?
Yes, because your permit is dependent on you living in Switzerland. A Schengen visa only allows you entry into the Area and doesn't include live/work rights. That's what your permit gives you. You don't have the right to live in Italy as your job is based in Switzerland and it's Switzerland who grants you the right to live/work here. Non-EU nationals are required to live in the same canton as their workplace is situated in.
As far as rooms are concerned usually only living room, dining room if separate, and bedrooms are counted. So 3 rooms means a living room and 2 bedrooms. 3.5 would be a living/dining room (the half being the dining area) combined with 2 bedrooms. 4 rooms could be either living, separate dining and 2 beds or living room and 3 beds - you need to check the actual details to be sure. So look for 4 rooms and above to be pretty sure of having 3 bedrooms.