The Bosch and Miele units by utilizing advancement filtration and water sensors using from 3-4 gallons amongst the lowest.

Probably not as the tops are generally porcelain so a baked on enamel finish at the factory. If  electric then you could replace the top but would be costly.

Tough call but the best of the best for me is the  La Cornue Chateua series , just an amazing product hand made in France. Sold a bunch over the years and they are a work of art.

https://www.lacornueusa.com/chateau