Marcella was very helpful and responded almost immediately. She even had her fried Gaia pick us up from the ferry stop near the apartment. The apartment itself was just as described. In terms of location, the apartment is close to a ferry stop called 'Fondamente Nove' which is great because it is very well connected to all stops including Murano / Burano. But it is a bit far away from the touristy stops (it is faster to walk than take the ferries).
(P.S. We were in Venice in October and on the last day it got fogged in and they stopped the ferries. So we had to drag our luggage for about 1.5 km all the way to the station.)