Hey Fish, cool concept. The best way to know how to paint water is to use reference. As far as the perspective is concerned, You need to create a vanishing point on the horizon line for each house. Your composition is also very heavy on the left, and you should balance it out by adding something to the right side. I did a quick, ugly sketch to show you what I'm getting out. Hope this helps :)

The colours look ok, just a bit overall on the cool side and neutral (which is fine as long as there's some more saturated colours in areas you want to highlight). I would definitely brighten up the bug with warm orange/reds and perhaps make the roofs of the houses warmer too. Compositionally, the house at the lower right sort of feels like it's interrupting the flow from the bugs in the water to the main bug. Try moving it more out of the scene to see the beach, then you can move the bugs more into the scene instead of where they are which feels a bit squished in. Hope that's helpful, composition is hard and I really like your concept and style here, great work!