I think water taxi has a surcharge for over 4. Will confirm if I can find my taxi rate book. As a practical matter, I think 6 with a lot of luggage will not fit.

A new system has been instuted at the airport. You pay for your taxi at a counter in the airport, and get a receipt. Give the receipt to the driver. Prices are much more favorable than direct dealing with the driver. I think VCE to the Danieli was €85, as there is a luggage surcharge also.