Pond plants and snails (Howey LD1)

Sweet Flag, suitable for any size pond, about 2 to 5 cms water depth.
White/Yellow lily, over 30 cm leaves, many flowers, our pond is 6 x 2 x 1m and this needs controlling.
Giant Marigold, big yellow flowers, does what it says on the can' needs control.
Bogbean and a plant with small yellow flowers.
Large clean snails, 3 varieties and water shrimp.
Butomus umbellatus perhaps.