We are allowed to park at the rental car parking lot, or was convenient and free!
No, there is no parking and you don't want a car in this part of Florence.
Having a car in Florence may be a bad idea anyway
I do not not know if they have off site parking. But I did not see a parking area in the hotel.
Not really sure you have to ask the hotel. As you know driving and parking in Florence is always interesting but because it is a luxury hotel I'm sure they must have some kind of accommodations. It's worth it.
Get an answer from Portrait Firenze staff and past guests.