3.2" TFT with Touch and crap, and it really eats a lot of pins (40 if I'm correct)
I'm sure you can get an inexpensive 240VAC -> 120VAC converter from one of those Chinese websites... should only need 1 converter for a bunch of Aqualifters, as they are only about 3W each.
Try 2-3 pins.And they have others, their new one is 4.3"
I like your idea of saving servos very much. Maybe another stepper motor "trolley" on the first "trolley", moving a servo with a little "fork" on the arm. Will have to think about that a bit I could probably save about 8 servos or so in the finished setup.
Along those lines I wonder if a poultry nipple would work better. A poultry nipple is a little $2 valve that chickens peck at to get a drop of water (see youtube for examples). Obviously it would be much simpler pushing the nipple with a servo rather than turning a valve. It's a lot more fun pushing nipples too.